Why do people have antibodies against other blood types?

The ABO blood type divides each blood type according to whether they have the "A" and "B" antigen(s) (AB has both, O has none). People also have antibodies against the antigens they don't have (AB has none, O has both), even before they have ever come in contact with those antigens.

Why do people have antibodies against these antigens they have never come in contact with? This isn't the normal situation for the immune system (e.g. for a virus or the blood type rhesus factor)

According to the Wikipedia entry for the ABO blood group system:

Anti-A antibodies are hypothesized to originate from immune response towards influenza virus, whose epitopes are similar enough to the α-D-N-galactosamine on the A glycoprotein to be able to elicit a cross-reaction. Anti-B antibodies are hypothesized to originate from antibodies produced against Gram-negative bacteria, such as E. coli, cross-reacting with the α-D-galactose on the B glycoprotein.

The cited reference is Van Oss, CJ (2004) Letter to the Editor: "Natural versus Regular Antibodies The Protein Journal 23:357, available here. This source contains this statement:

… "we have known for more than four decades that these bloodgroup (antibodies) arise out of minor infections occurring very early in life… "

The cited references are:

Pettenkofer et al. Z. ImmunForsch. 119: 415-429

Springer, GF (1960) Klin. Wschr. 38: 513-514

Unfortunately I have access to neither of these articles, and besides they are presumably written in German.

We each inherit either A, B, AB or no antigens from our parents.

The current thought is that when you're between 0-6 months old you are exposed to bacteria/viruses that contain very similar antigens (A or B). These antigens are similar enough to the A and B antigens found on red blood cells that any antibody created against these bacterial antigens would also react against the corresponding red blood cell antigen. Seeing as you can't produce an antibody against your own antigen (except in rare circumstances), you always produce the opposite antibody to what antigen you have.

I hope some of that makes sense. Feel free to point out any glaring mistakes I've made, wouldn't be the first time! ;-)

Source: I'm a biomedical scientist.

I am posting so long after the initial question as I replied to a more recent similar question that was marked as a duplicate. On being redirected here I was surprised at the answers as the question (and certainly that of the supposed duplicate) did not give any indication that he was aware that the situation for non-compatible blood-group antigens was any different from any other foreign antigens. I think it appropriate, therefore, to append the following (@KennyPeanuts has also commented in this vein) for the benefit of those unfamiliar with the idea of clonal selection.

To put it simply, clonal theory of antibody selection assumes that the antigen-specificity of antibody-producing cells is random, so that all types of specificity will exist. On encountering an antigen a particular cell will be stimulated to divide and hence allow the production of a greater amount of antibody against the antigen.

Immune tolerance requires that cells producing antibody against self antigens be eliminated at some stage. Hence people of blood group O, lacking blood-group antigens A and B, will not have become tolerant to them, and will have antibody-producing cells capable of producing antibodies against them, should they encounter them in an incorrect blood transfusion.

What are antibodies?

Our body has a specialized search-and-destroy army. Antibodies are key players in that fight.

Antibodies are specialized, Y-shaped proteins that bind like a lock-and-key to the body's foreign invaders — whether they are viruses, bacteria, fungi or parasites. They are the "search" battalion of the immune system's search-and-destroy system, tasked with finding an enemy and marking it for destruction.

"They're released from the cell and they go out and hunt," said Dr. Warner Greene, the director of the Center for HIV Cure Research at the Gladstone Institutes in San Francisco.

When antibodies find their target, they bind to it, which then triggers a cascade of actions that vanquish the invader. Antibodies are part of the so-called "adaptive" immune system, the arm of the immune system that learns to recognize and eliminate specific pathogens, Greene said.

What about plasma donations?

Although people often donate whole blood, platelets and plasma from donors are also used. Donations are separated into different components before transfusions occur, depending on the needs of the recipient.

Your blood type is important not only when it comes to donations of red cells, but also when we’re talking about donations of plasma, which contains certain antibodies depending on your blood type. So, if someone with Type O blood was to try and donate plasma to someone with Type B blood, that plasma would contain anti-A and anti-B antibodies. Those anti-B antibodies would then attack the red blood cells of the Type B recipient.

What is the significance of antigens during transfusions?

You might have heard the terms &lsquouniversal donor&rsquo and &lsquouniversal recipient&rsquo before. What these refer to is an individual&rsquos ability to accept blood from another human. If the blood types are not compatible, red blood cells will clump together, forming clots that can block blood vessels and cause death.

Since Group O- has none of the three antigens, but does have all three antibodies, their bodies react violently to a transfusion from a blood Group that might have any kind of antigen. Hence, they can only receive blood from another Group O- individual. The absence of antigens also gives them the ability to donate blood to anyone, so these individuals are called &lsquoUniversal Donors&rsquo. Similarly, since Group AB+ people have all three antigens and none of the antibodies, so they can accept blood from any individual without risk. This makes them &lsquoUniversal Recipients&rsquo.

Red Blood Cell Compatibility Chart

How Do Blood Type, Stress, Emotional Alignment, and Cell Membrane Health Influence Susceptibility to Infections?

Emily Chan, ND

The internal environment of the body highly affects susceptibility to infection. How can one person develop influenza, while a coworker in the next cubicle remains healthy, when both are exposed to the same office conditions? To reduce the likelihood of succumbing to infectious disease, it is important to understand the factors that contribute to infection and to promote the factors that support increased resistance to infection.

History of the Germ Theory

In the late 1800s, Louis Pasteur was credited with developing the germ theory, a hypothesis that proposes that microorganisms are responsible for the development of infectious diseases. Similarly, during the same period, Robert Koch proposed the theory of contagionism, which argues that disease is transmitted from person to person through inoculation, touch, proximity, and indirect transmission. 1 Primarily due to political and economic reasons of the times, the proposals by Koch for quarantine, disinfection, and boiling of water to prevent cholera were not well received because of the inconveniences that isolation had on manufacturing, trading, and exporting. 1 Despite the controversy he was met with, the germ theory has become a predominant cornerstone of modern medicine.

In a futile attempt to falsify the now-dominant germ theory, Max von Pettenkofer, a highly respected public health figure, swallowed the bacteria that allegedly caused cholera, proposing that disease would occur only in susceptible individuals. 1 Healthy individuals can remain healthy in the face of exposure, but infection can set in among susceptible individuals, despite measures of disinfection and quarantine.

Although the germ theory by Pasteur and Koch led to many advances in modern medicine, including an increase in hygiene and the discovery of penicillin, it narrowed the medical research paradigm that would be followed for most of the 20th century. 2 As a result of this focus, medicine became militaristic: identify the enemy (disease) and its source (microbe) and then exterminate it methodically and absolutely. Such a militaristic concept of health created a hypochondriacal view of one’s environment, causing individuals to reduce social and environmental contacts (eg, sewer gases, public telephones, and touching someone who has a cold) for fear of contamination. 2

Rudolph Virchow said, “Mosquitos seek the stagnant water, but do not cause the pool to become stagnant,” 3(p) illustrating the importance of a healthy internal environment. This article will discuss factors that are less commonly considered relative to infectious disease.

Individuals of different blood groups may have varying susceptibilities to influenza A or B strains. Reviewing some basic information about blood type will help to understand why this is. The differences among the 4 blood groups lie in the variance of carbohydrate and protein molecules attached to the blood cells. These glycoproteins serve as tags on the blood cell. 4 The blood type is present in other body fluids besides blood (eg, saliva) and in the lining of mucous membranes among most of the population. Due to the presence on mucosa, different blood types can affect the interaction and adhesion of microbes to the mucous membranes and influence susceptibility to infection. 4

Besides providing information on epidemiology, knowledge of one’s blood type can give more specific information on diet, nutritional supplements, and susceptibility to infection and assist in personal decisions such as whether to receive a swine flu vaccine. It should be noted that influenza strains A and B and blood types A and B are named similarly but refer to different things. Caution should be exercised so that confusion between the 2 is avoided.

Individuals with blood type O have the ability to generate antibodies against influenza A viruses (such as H1N1 or H3N2) and have good resistance against influenza B viruses. Blood type O individuals produce higher levels of hemagglutinin antibodies against influenza A than other blood types, and in many instances this has allowed for a decrease in their susceptibility to this virus. 5

Individuals with blood type B are efficient at generating antibodies against influenza B viruses however, this blood type is more susceptible to influenza A viruses such as H1N1 or H3N2. Individuals with type B blood have slower antibody production against influenza A viruses therefore, these viruses may replicate faster than the body can expel or reject them. 6

An epidemiological survey showed that children with type B blood may serve as latent carriers for influenza A viruses, possibly contributing to the emergence of new epidemic strains in countries of Southeast Asia. 6 The study demonstrated that circulating influenza A viruses may be present in 10% to 36% of healthy children in Asia (a region with a larger percentage of individuals with type B blood than America) up to 5 months before the onset of a new influenza epidemic. These antigens (influenza viruses) may also be present for up to 5 months after these individuals have had influenza, thereby making them likely carriers of the virus, infecting others in their “nonsick state.” 6

Individuals with blood type A have the ability to quickly generate antibodies against influenza A viruses such as H1N1 and H3N2 in particular. 7 In addition, they tend to have a stronger immune response to more virulent strains of type A viruses and a poorer response to less virulent strains, including the less virulent influenza B strains. 7,8 In the face of more severe influenza epidemics, blood type A individuals may be at an advantage.

Individuals with blood type AB have the poorest ability to generate antibodies against any of the influenza virus strains compared with the other blood types. 7 One hypothesis as to why this may be is that blood type AB individuals do not generate any anti-A or anti-B antibodies. Because blood type AB can receive any blood type in transfusions, their immune systems may metaphorically be more “friendly” and less defensive against other blood types, as well as microbes.

In a swine flu (H1N1) study 9 among military subjects, those with blood types A and B were able to seroconvert to antibody titers exceeding 20, whereas subjects with blood type AB were limited to the antibody titer level of 10. Seroconversion is essential for developing detectable levels of specific antibodies to an infectious agent. 10 If individuals with blood type AB have a poorer ability to develop a sufficiently high antibody titer level, they may not mount enough of an immune response to prevent infection.

Clinical Relevance

The information presented reflects tendencies of individuals with different blood types in their susceptible states. Data on genetic predispositions serve to reveal where weak links are so that measures can be taken to work around them. The following are antiviral and immune-supporting supplements for the different blood types based on research by D’Adamo and Whitney. 11

Type O. Astragulus membranaceus, Picrorhiza kurroa, l-glutamine, Isatis tinctoris (woad root), Ganoderma senensis (Reishi mushroom), Andrographis paniculata, and Ligusticum porteri (osha root).

Type B. Coriolus versicolor mushroom, Eleutherococcus senticosus (Siberian ginseng), Tribulus terrestris, Chlorella, Grifola frondosa (Maitake mushroom), Cordyceps sinensis, Job’s tears, l-arginine, and Salvia officinalis (sage).

Type A. Panax ginseng, Tilia (linden), Polygonum multiflorum (fo-ti), Morinda citrifolia (noni), zinc, vitamin A, vitamin C, and Astragulus membranaceus.

Type AB. Tilia (linden), l-arginine, Chlorella, Eleutherococcus senticosus (Siberian ginseng), zinc, Astragulus membranaceus, Ganoderma senensis (Reishi mushroom), and vitamin C.

All Types. Probiotics, larch arabinogalactan, and elderberry.

Social Factors

Physical conditions are not the only contributing factors to disease susceptibility. There are many other examples of environmental and social influences that can have a significant effect on the body’s ability to fight disease.

The benefits of touch are well known for the survival and development of infants. Investigations show that preterm infants given therapeutic touch had decreased heart rates and respiratory rates, demonstrated increased ability to rest, developed better sucking and swallowing when feeding, and showed a greater ability to engage with the environment. 12 Two minutes of skin-to-skin contact before vaccination injections reduced pain in infants. 13

Touch also has positive effects on the immune system. A study 14 was conducted on the effects of therapeutic touch on suppressor T-cell count. Suppressor T cells inhibit the immune system by suppressing antibody production. Patients receiving 40 minutes of therapeutic touch had an 18% decrease in suppressor T cells after the session, showing that immune function was enhanced by touch.

Chronic stress and depression can lower immune function. This can contribute to increased susceptibility to infection and reactivation of latent viruses such as herpes and Epstein-Barr viruses. 15

A study 16 conducted among undergraduate students in Amsterdam, the Netherlands, showed that stress changed the protein composition of saliva, increasing adhesion of pathogenic oral bacteria such as Streptococcus mitis in the oral cavity and Helicobacter pylori in the gastrointestinal mucosa. It was further found that oral colonization of Candida albicans required coadhesion with oral streptococcal organisms such as Streptococcus gordonii. The autonomic nervous system controls the salivary glands, and under the influence of sympathetic stimulation, secreted salivary proteins are different from proteins secreted in a calm state. Stress stimuli in the study included a time-pressured memory test and a video presentation showing various surgical operations. Subjects under stress produced salivary proteins that increased microbial adherence, which is needed for bacterial colonization and infection.

It may seem that the Amsterdam study 16 pertains only to oral health. However, the microbial colonization processes discussed herein are not unique to the oral mucosa but take place on other mucosal surfaces such as the throat, lungs, gastrointestinal tract, and genitourinary tract. Proteins in mucous secretions of the respiratory tract and gastrointestinal tract mediate these processes. Therefore, stress can affect how likely it is that a microbe will adhere and infect different body systems.

Emotional Alignment

Positive emotional style is associated with feeling lively, full of pep, energetic, happy, pleased, cheerful, at ease, calm, and relaxed. Negative emotional style is associated with feeling sad, depressed, unhappy, on edge, nervous, tense, hostile, resentful, and angry. 17 An emotional style is not fixed and can be learned and developed. Does living predominantly by certain character traits have an effect on the immune system?

Three hundred thirty-four healthy men and women aged 18 to 54 years were investigated at the University of Pittsburgh, Pittsburgh, Pennsylvania, to observe the association of positive emotional style or negative emotional style with susceptibility to the common cold. The subjects with administered nasal drops containing rhinoviruses and were monitored to see whether they developed colds. 17

Subjects who tended to demonstrate a positive emotional style exhibited fewer cold symptoms such as congestion, runny nose, sneezing, cough, sore throat, malaise, headache, and chills in contrast, those who tended toward a negative emotional style exhibited more cold symptoms. 17 In addition, having a positive emotional style reduced the likelihood of being infected with the cold virus, although the data did not reach statistical significance. Another study 18 showed that sociability (characterized by extraversion, agreeableness, and positive relationships) was linked to decreased susceptibility to infection by the cold virus.

Positive mood can enhance the immune system by increasing IgA antibodies, 17 which are generally associated with protection against infection. 19 Negative mood can be correlated with an alteration in the production of cortisol, which then increases production of proinflammatory cytokines that are responsible for the signs and symptoms of illness. 17 Cytokines are the chemical molecules that bring about body aches and pains, increased mucous production, and swelling during illness. 20 These are only few mechanisms by which mood affects physiology.

Clinical Relevance

As medical providers, it is our responsibility to support the health of the entire person, not merely physical health, as physical health is affected by mental and emotional health. Stress or negative feelings are often thought of as brought on by circumstances. However, we have no control over other people or our surroundings, but we can control how we respond to them. It behooves us as practitioners to support the needs of patients and to refer them if necessary to obtain resources that enable them to embark on personal growth and to engage in lifestyle and behavioral patterns that are supportive to the immune system and to general health.

Cell Membrane HEALTH

What appears to be merely a jacket of the cell actually functions in many more capacities. The cell membrane is responsible for regulating the flow of positive and negative ions and for maintaining negative charge within the cell. Membrane proteins serve to communicate with other cells or to respond to substances secreted by other cells. 21 The components of the cell membrane itself influence inflammation. For example, cell membranes composed of more omega-3 fatty acids are less inflammatory than cell membranes composed of a greater amount of arachadonic acid. 22

It is my hypothesis that the more negative is the cell membrane potential (optimally −80 mV), the less likely it is that the cell will be infected. From bacterial investigations, it is known that, if the net negative charge of the cell membrane is lowered, a bacterium is more resistant to antibiotic penetration. 23 The mechanism involves the addition of amino acids to the phosphatidylglycerol of the cell membrane, lowering the charge potential of the membrane and in effect rendering the cell membrane less penetrable. 23

One study 24 showed how respiratory syncytial virus binds to cell surface glycosaminoglycans and how different glycosaminoglycans may influence infection. Another study 22 demonstrated that fatty acid composition of cell membranes affects inflammation and cytokine release. Increased amounts of arachadonic acid are proinflammatory. Higher amounts of inflammatory cytokine release can increase symptoms and severity of infectious illness. 20 Therefore, the healthier the cell membrane is, the less likely it is that a cell would be susceptible to infection.

The clinical relevance is that bioimpedance analysis is a clinical tool that can be used to monitor the health of cells and body composition. There are several clinical measures that support improved cell membrane function. An alkaline diet, electrolyte supplementation, and adrenal support can increase intracellular water and negative cell membrane potential. Adequate protein intake is generally supportive of proper cell surface protein receptors, which are essential for cell-to-cell communication. Vitamin C, bioflavonoids, MSM, and amino acids support glycosaminoglycans and connective tissue. Finally eicosapentaenoic acid, DHA,borage oil, and olive oil are healthy fats that decrease inflammation.


Blood type, social factors, and cell membrane health can affect susceptibility to infectious disease. However, susceptibilities are not predestinations. Gene expression can be manipulated by using certain supplements or by making lifestyle changes. Countless resources to learn how to manage stress and to develop healthier lifestyle patterns are available. Finally, there are many naturopathic therapies that support proper cell function. Therefore, as knowledge is gained on factors that affect susceptibility to infection, tools can be used to modulate and reduce those tendencies.

The objective of this article is to rekindle a sense of empowerment. We are not at the mercy of microbes. We are not bound by our genetic inheritance. We are not victims of our social environments. We are not limited by our physical health. Rene Dubois says, “Viruses and bacteria are not the sole cause of infectious disease there is something else.”

This information is for educational purposes only and is not intended to diagnose or treat disease.

Emily Chan, ND graduated Summa Cum Laude from California State University Hayward, with a BS in biology and a minor in music. While a doctorate student at Bastyr University she interned at the Functional Medicine Research Center and Emergency Department at Evergreen Hospital.

Dr. Chan’s interest in world wide humanitarian efforts led her to Beijing China, where she worked with disabled children. Through her efforts to further education in others, Dr. Chan currently holds numerous speaking engagements throughout Massachusetts, New York, and Washington State.

Dr. Chan performs with local orchestras and appears regularly on a local access television program titled “A Healer in Every Home”. She currently practices in Cambridge, Massachusetts at the Lydian Center for Innovative Medicine.

1. Oppenheimer GM, Susser E. Invited commentary: the context and challenge of von Pettenkofer’s contributions to epidemiology. Am J Epidemiol. 2007166(11):1239-1241.

2. An PG. Constructing and dismantling frameworks of disease etiology: the rise and fall of sewer gas in America, 1870-1910. Yale J Biol Med. 200477(3-4):75-100.

3. Jones DS, ed. Textbook of Functional Medicine. Gig Harbor, WA: Institute for Functional Medicine 2005.

4. D’Adamo P. Live Right for Your Type. New York, NY: Penguin Putnam Inc 2000.

5. Mackenzie JS, Fimmel PJ. The effect of ABO blood groups on the incidence of epidemic influenza and on the response to live attenuated and detergent split influenza virus vaccines. J Hygiene (Lond). 197880(1):21-30.

6. Sominina AA, Tsubalova LM, Karpova LS, et al. Genetic predisposition to latent influenza A virus in children with blood type B(III) as a possible cause of new epidemiologic strains in the countries of South-Eastern Asia [in Russian]. Vestn Ross Akad Med Nauk. 1994(9):21-24.

7. Eat Right for Your Type Web site. D’Adamo P, Kelly G. Blood groups and influenza. Accessed August 7, 2010.

8. Karpova LS, Popova TL, Oleinikova EV, Popova RP, Karpukhin GI. Significance of persons with different blood groups in the influenza type A epidemic process [in Russian]. Zh Mikrobiol Epidemiol Immunobiol. 1982(11):86-91.

9. Lebiush M, Rannon L, Kark JD. The relationship between epidemic influenza (A(H1N1) and ABO blood group. J Hyg (Lond). 198187(1):139-146.

10. Goldsby RA, Kindt TJ, Kuby J, Osborne BA, eds. Immunology, Fifth Edition. New York, NY: WH Freeman 2002.

11. D’Adamo P, Whitney C. Eat Right for Your Type Complete Blood Type Encyclopedia. New York, NY: Penguin Group 2002.

12. Hanley MA. Therapeutic touch with preterm infants: composing a treatment. Explore (NY). 20084(4):249-258.

13. Chermont AG, Falcão LF, de Souza Silva EH, de Cássia Xavier Balda R, Guinsburg R. Skin-to-skin contact and/or oral 25% dextrose for procedural pain relief for term newborn infants. Pediatrics. 2009124(6):e1101-e1107.

14. Gerber R. Vibrational Medicine for the 21st century. New York, NY: HarperCollins Publisher Inc 2000.

15. Godbout JP, Glaser R. Stress-induced immune dysregulation: implications for wound healing, infectious disease and cancer. J Neuroimmune Pharmacol. 20061(4):421-427.

16. Bosch JA, Turkenburg M, Nazmi K, Veerman EC, de Geus EJ, Nieuw Amerongen AV. Stress as a determinant of saliva-mediated adherence and coadherence of oral and nonoral microorganisms. Psychosom Med. 200365(4):604-612.

17. Cohen S, Doyle WJ, Turner RB, Alper CM, Skoner DP. Emotional style and susceptibility to the common cold. Psychosom Med. 200365(4):652-657.

18. Cohen S, Doyle WJ, Turner R, Alper CM, Skoner DP. Sociability and susceptibility to the common cold. Psychol Sci. 200314(5):389-395.

19. Stone AA, Cox DS, Valdimarsdottir H, Jandorf L, Neale JM. Evidence that secretory IgA antibody is associated with daily mood. J Pers Soc Psychol. 198752(5):988-993.

20. Dobbs CM, Feng N, Beck FM, Sheridan JF. Neuroendocrine regulation of cytokine production during experimental influenza viral infection: effects of restraint stress–induced elevation in endogenous corticosterone. J Immunol. 1996157(5):1870-1877.

21. Sliverthorn DU. Human Physiology: An Integrated Approach. Upper Saddle River, NJ: Prentice-Hall Inc 2001.

22. Calder PC. Fatty acids and immune function: relevance to inflammatory bowel diseases. Int Rev Immunol. 200928(6):506-534.

23.⋅Roy H. Tuning the properties of the bacterial membrane with aminoacylated phosphatidylglycerol. IUBMB Life. 200961(10):940-953.

24. Hallak LK, Kwilas SA, Peeples ME. Interaction between respiratory syncytial virus and glycosaminoglycans, including heparan sulfate. Methods Mol Biol. 2007379:15-34.

22. Thethi K, Duszyk M. Decreased cell surface charge in cystic fibrosis epithelia. Cell Biochem Function. 199715(1):35-38.

What are Antibodies?

(aka immunoglobulins) are proteins produced and secreted by differentiated B-lymphocytes called plasma cell. They mediate the humoral immune response and are necesassary for the determination of self versus foriegn antigens. Antibodies have an interesting Y-shaped structure withat least two binding sites for one specific antigen. The areas where the antigen is recognized on the antibody are variable domains. Importantly, antibodies mark pathogens for destruction by phagocytic cells, such as macrophages or neutrophils. Because phagocytic cells are highly attracted to molecules complexed with antibodies, cells or antigens that are tagged with antibodies will eventually be engulfed and destroyed.

Antibodies and ABO Blood Types

Normally the body must be exposed to a foreign antigen before an antibody can be produced. This is not the case for the ABO blood group. Individuals with type A blood&mdashwithout any prior exposure to incompatible blood&mdashhave preformed antibodies to the B antigen circulating in their blood plasma. These antibodies, referred to as anti-B antibodies, will cause agglutination and hemolysis if they ever encounter erythrocytes with B antigens. Reviewing thelook at the table below:

      • &rarr Blood type A has Anti-B antibodies circulating in their blood.
      • &rarr Blood type B has Anti-A antibodies circulating in their blood.
      • &rarr Blood type AB has neither Anti-A antibodies, nor Anti-B antibodies circulating in their blood.
      • &rarr Blood type O has both Anti-A and Anti-B antibodies circulating in their blood

      Similarly, an individual with type B blood has pre-formed anti-A antibodies. Individuals with type AB blood, which has both antigens, do not have preformed antibodies to either of these. People with type O blood lack antigens A and B on their erythrocytes, but both anti-A and anti-B antibodies circulate in their blood plasma.

      • &rarr Blood Type A has A-antigens
      • &rarr Antibodies locate antigens and target them for degradation via phagocytes.

      If blood type A had Anti-A antibodies, those antibodies would attach that individuals own blood cells! For this reason, you will have the antibodies that only recognize antigens that are not already on your blood cells.

      Blood Types

      Blood transfusions are a lifesaving treatment for many Americans. Blood transfusions are needed for many reasons, including surgery, after accidents, and for patients with illnesses and cancer.

      Blood cannot be artificially made, so doctors rely on volunteer donations. To keep the blood supply safe, every donation is tested for blood type and checked for infectious diseases.

      What Are the Components of Blood?

      All blood contains the same basic components:

      But not everyone has the same blood type.

      What Are the Blood Types?

      Categorizing blood according to type helps prevent reactions when someone gets a blood transfusion. Red blood cells have markers on their surface that characterize the cell type. These markers (also called antigens) are proteins and sugars that our bodies use to identify the blood cells as belonging in us.

      The two main blood groups are ABO and Rh.

      The ABO blood system has four main types:

      • Type A: This blood type has a marker known as A.
      • Type B: This blood type has a marker known as B.
      • Type AB: This blood type has both A and B markers.
      • Type O: This blood type has neither A or B markers.

      Blood is further classified as being either "Rh positive" (meaning it has Rh factor) or "Rh negative" (without Rh factor).

      So, there are eight possible blood types:

      1. O negative. This blood type doesn't have A or B markers, and it doesn't have Rh factor.
      2. O positive. This blood type doesn't have A or B markers, but it does have Rh factor. O positive blood is one of the two most common blood types (the other being A positive).
      3. A negative. This blood type has A marker only.
      4. A positive. This blood type has A marker and Rh factor, but not B marker. Along with O positive, it's one of the two most common blood types.
      5. B negative. This blood type has B marker only.
      6. B positive. This blood type has B marker and Rh factor, but not A marker.
      7. AB negative. This blood type has A and B markers, but not Rh factor.
      8. AB positive. This blood type has all three types of markers — A, B, and Rh factor.

      Having any of these markers (or none of them) doesn't make a person's blood any healthier or stronger. It's just a genetic difference, like having green eyes instead of blue or straight hair instead of curly.

      Why Are Blood Types Important?

      The immune system is the body's protection against invaders. It can identify antigens as self or nonself. To get a blood transfusion safely, a person's immune system must recognize the donor cells as a match to his or her own cells. If a match isn't recognized, the cells are rejected.

      The immune system makes proteins called antibodies that act as protectors if foreign cells enter the body. Depending on which blood type you have, your immune system will make antibodies to react against other blood types.

      If a patient gets the wrong blood type, the antibodies immediately set out to destroy the invading cells. This aggressive, whole-body response can give someone a fever, chills, and low blood pressure. It can even cause vital body systems — like breathing or the kidneys — to fail.

      Here's an example of how the blood type-antibody process works:

      • Let's say you have type A blood. Because your blood contains the A marker, it makes B antibodies.
      • If B markers (found in type B or type AB blood) enter your body, your type A immune system gets fired up against them.
      • This means that you can only get a transfusion from someone with A or O blood, not from someone with B or AB blood.

      In the same way, if you have the B marker, your body makes A antibodies. So as a person with type B blood, you could get a transfusion from someone with B or O blood, but not A or AB.

      Things are a little different for people with type AB or type O blood:

      • If you have both A and B markers on the surface of your cells (type AB blood), your body does not need to fight the presence of either.
      • This means that someone with AB blood can get a transfusion from someone with A, B, AB, or O blood.

      But if you have type O blood, your red blood cells have neither A or B markers. So:

      • Your body will have both A and B antibodies and will therefore feel the need to defend itself against A, B, and AB blood.
      • A person with O blood can only get a transfusion with O blood.

      Can Teens Donate Blood?

      Blood transfusions are one of the most frequent lifesaving procedures hospitals do. Every 2 seconds someone needs a blood transfusion. So there's always a need for blood donors. One blood donation can save up to three lives.

      About 15% of blood donors are high school and college students. If you'd like to help, contact your community blood center. It's one way to be an everyday superhero and save lives!

      Blood Group Antibodies

      The red cells of an individual contain antigens on cell surfaces that correspond to their blood group. Antibodies in the serum that identify such antigen locate on the surfaces of red cells of another blood group. At present, 35 blood group systems representing over 300 antigens are listed by the International Society of Blood Transfusion (ISBT).

      Creative Diagnostics is your trustworthy partner for blood group antibodies since we offer a collection of highly specific blood group antibodies to meet your research requirement. With the core technology and the excellent team of scientists, Creative Diagnostics also provide custom service with high quality and high efficiency, which will definitely benefit your work with antibodies and always bring the best approach to overcome the obstacles on your way to success.

      What is blood group?
      The presence or absence of certain protein, antigens located on the surface of the red blood cells, and antibodies in the blood plasma, lead to the different types of blood groups. Heretofore, there are more than 300 human blood groups, but only about 20 are genetically-determined. Among these 20 blood groups, a very minority are clinically significant transfusion reactions, in which ABO and Rh systems are the most common ones.

      The ABO system
      The ABO system is the most important blood-group system in human-blood transfusion, since any person above the age of 6 months possess clinically significant anti-A and/or anti-B antibodies in their serum. Blood group A contains antibody against blood group B in serum and vice-versa, while blood group O contains no A/B antigen but both their antibodies in serum. This discovery is a tremendous progress in clinical transfusion practice to prevent fatal danger by ABO-incompatible blood transfusion.

      The Rh system
      The Rh system (Rh meaning Rhesus) is the second most significant blood-group system in human-blood transfusion including antigens of D (or Rho), C, E, c, and e, among which the D antigen is the most significant one. Those possessing D antigen on the surface of RBCs are Rh-positive, while other who lack D antigen are Rh-negative, no matter what other Rh antigens are present. The presence or absence of the Rh(D) antigen is signified by the + or ? sign, so that for example the A? group is ABO type A and does not have the Rh (D) antigen.

      Other clinically important blood group systems

      In addition to the ABO antigens and Rh antigens, many other antigens are expressed on the red blood cell surface membrane. For example, an individual can be AB, D positive, and at the same time M and N positive (MNS system), K positive (Kell system), Lea or Leb negative (Lewis system), and so on, being positive or negative for each blood group system antigen.

      What is blood group antibody?

      Blood group antibodies in the serum are the clinically significant antibodies, which can specially identify antigens locate on the surfaces of red cells of another blood group, typically for transfusion purposes. As we all know, if mixing incompatible blood groups, blood clumping or agglutination will occur. That is to say, transfusion reactions or hemolytic disease of the fetus and newborn (HDFN) are usually resulted from alloantibodies produced by the exposure to a different blood group by transfusion or pregnancy.

      The anti-A and anti-B activity prominently resides in IgM class, while only a few rests with IgG coating the RBCs with no effect on their viability but resulting in HDFN by crossing the placenta. Specially, those with O blood type regularly have more IgG anti-A and anti-B than any others.

      As a monomer with 2 Fab sites and a Fc portion carrying macrophage receptor, IgG, requires high concentration to activate complement, but only to C3 immune complexes, which is able to amplify extravascular hemolysis. Most IgGs can bind with related antigen on the red blood cells around the normal body temperature of 37°C, which are defined as warm antibodies and most clinically significant antibodies. On the other side, IgM, as a pentamer with 10 Fab sites and without the macrophage receptor, is the cold antibody that binds with Ag at ambient temperature or colder temperatures. IgMs do not usually cause clinical problems, but they may be picked up on laboratory testing since the polymers allow complement activation to C9 and intravascular hemolysis if reactivate at 37°C.

      The Mystery of Human Blood Types

      Blood banks run blood type tests before blood is sent to hospitals for transfusions. Image: U.S. Navy photo by Mass Communication Specialist 3rd Class Jake Berenguer/Wikicommons

      Everyone’s heard of the A, B, AB and O blood types. When you get a blood transfusion, doctors have to make sure a donor’s blood type is compatible with the recipient’s blood, otherwise the recipient can die. The ABO blood group, as the blood types are collectively known, are ancient. Humans and all other apes share this trait, inheriting these blood types from a common ancestor at least 20 million years ago and maybe even earlier, claims a new study published online today in Proceedings of the National Academy of Sciences. But why humans and apes have these blood types is still a scientific mystery.

      The ABO blood group was discovered in the first decade of the 1900s by Austrian physician Karl Landsteiner. Through a series of experiments, Landsteiner classified blood into the four well-known types. The “type” actually refers to the presence of a particular type of antigen sticking up from the surface of a red blood cell. An antigen is anything that elicits a response from an immune cell called an antibody. Antibodies latch onto foreign substances that enter the body, such as bacteria and viruses, and clump them together for removal by other parts of the immune system. The human body naturally makes antibodies that will attack certain types of red-blood-cell antigens. For example, people with type A blood have A antigens on their red blood cells and make antibodies that attack B antigens people with type B blood have B antigens on their red blood cells and make antibodies that attack A antigens. So, type A people can’t donate their blood to type B people and vice versa. People who are type AB have both A and B antigens on their red blood cells and therefore don’t make any A or B antibodies while people who are type O have no A or B antigens and make both A and B antibodies. (This is hard to keep track of, so I hope the chart below helps!)

      After Landsteiner determined the pattern of the ABO blood group, he realized blood types are inherited, and blood typing became one of the first ways to test paternity. Later, researchers learned ABO blood types are governed by  a single gene that comes in three varieties: A, B and O. (People who are type AB inherit an A gene from one parent and a B gene from the other.)

      This chart lists the antigens and antibodies made by the different ABO blood types. Image: InvictaHOG/Wikicommons

      More than a hundred years after Landsteiner’s Nobel Prize-winning work, scientists still have no idea what function these blood antigens serve. Clearly, people who are type O—the most common blood type—do just fine without them. What scientists have found in the last century, however, are some interesting associations between blood types and disease. In some infectious diseases, bacteria may closely resemble certain blood antigens, making it difficult for antibodies to detect the difference between foreign invaders and the body’s own blood. People who are type A, for instance, seem more susceptible to smallpox, while people who are type B appear more affected by some E. coli infections.

      Over the last hundred years, scientists have also discovered that the ABO blood group is just one of more than 20 human blood groups. The Rh factor is another well known blood group, referring to the “positive” or “negative” in blood types, such as A-positive or B-negative. (The Rh refers to Rhesus macaques, which were used in early studies of the blood group.) People who are Rh-positive have Rh antigens on their red blood cells people who are Rh-negative don’t and produce antibodies that will attack Rh antigens. The Rh blood group plays a role in the sometimes fatal blood disease erythroblastosis fetalis that can develop in newborns if an Rh-negative women gives birth to an Rh-positive baby and her antibodies attack her child.

      Most people have never heard of the numerous other blood groups—such as the MN, Diego, Kidd and Kell—probably because they trigger smaller or less frequent immune reactions. And in some cases, like the MN blood group, humans don’t produce antibodies against the antigens. One “minor” blood type that does have medical significance is the Duffy blood group. Plasmodium vivax, one of the parasites that causes malaria, latches onto the Duffy antigen when it invades the body’s red blood cells. People who lack the Duffy antigens, therefore, tend to be immune to this form of malaria.

      Although researchers have found these interesting associations between blood groups and disease, they still really don’t understand how and why such blood antigens evolved in the first place. These blood molecules stand as a reminder that we still have a lot to learn about human biology.

      Blood Types

      Blood types are determined by the presence or absence of certain antigens – substances that can trigger an immune response if they are foreign to the body. Since some antigens can trigger a patient's immune system to attack the transfused blood, safe blood transfusions depend on careful blood typing and cross-matching. Do you know what blood type is safe for you if you need a transfusion?

      There are four major blood groups determined by the presence or absence of two antigens – A and B – on the surface of red blood cells. In addition to the A and B antigens, there is a protein called the Rh factor, which can be either present (+) or absent (–), creating the 8 most common blood types (A+, A-, B+, B-, O+, O-, AB+, AB-).

      Blood Types and Transfusion

      There are very specific ways in which blood types must be matched for a safe transfusion. The right blood transfusion can mean the difference between life and death.

      Every 2 seconds someone in the US needs a blood transfusion.

      Use the interactive graphic below to learn more about matching blood types for transfusions.

      Also, Rh-negative blood is given to Rh-negative patients, and Rh-positive or Rh-negative blood may be given to Rh-positive patients. The rules for plasma are the reverse.

      • The universal red cell donor has Type O negative blood.
      • The universal plasma donor has Type AB blood.

      There are more than 600 other known antigens, the presence or absence of which creates "rare blood types." Certain blood types are unique to specific ethnic or racial groups. That’s why an African-American blood donation may be the best hope for the needs of patients with sickle cell disease, many of whom are of African descent. Learn about blood and diversity.

      What Is A Universal Blood Donor?

      Universal donors are those with an O negative blood type. Why? O negative blood can be used in transfusions for any blood type.

      Type O is routinely in short supply and in high demand by hospitals – both because it is the most common blood type and because type O negative blood is the universal blood type needed for emergency transfusions and for immune deficient infants.

      Approximately 45 percent of Caucasians are type O (positive or negative), but 51 percent of African-Americans and 57 percent of Hispanics are type O. Minority and diverse populations, therefore, play a critical role in meeting the constant need for blood.

      Types O negative and O positive are in high demand. Only 7% of the population are O negative. However, the need for O negative blood is the highest because it is used most often during emergencies. The need for O+ is high because it is the most frequently occurring blood type (37% of the population).

      The universal red cell donor has Type O negative blood. The universal plasma donor has Type AB blood. For more about plasma donation, visit the plasma donation facts.