blood group
- There are certain molecules on the surfaces of cell in the body that can be recognized as foreign by the immune system of another individual and hence can induce the immune system of latter.
- These molecules are known as antigens. As part of the immune response, particular lymphocytes, secretes a class of protein called antibodies that bind in a specific fashion with antigens.
- The membranes of red blood cells (RBCs) als posses several antigens. Depending on the nature of antigens present on the red blood cells(RBCs) also posses several antigens.
- Depending on the nature of antigens present on the membrane of RBCs, various types of blood grouping have been done. Two such groupings are- the ABO and Rh- are widely used all over the world.
ABO grouping
- Karle Landsteiner (1901) along with his coworker recognised four types of blood groups- in human beings, commonly known as ABO blood grouping.
- ABO grouping is based on the presence of two surfaces antigens on the RBCs namely A and B. Similarly, the plasma of different individual also contain two natural antibodies called anti- A and anti-B.
Transfusion Reactions
- In many clinical conditions blood transfusion is needed. In such cases the donor’s blood and recipient’s blood must be compatible to avoid severe problems of clumping (destruction of RBC).
- A major cross- match is made by mixing serum from the recipient with blood cells from the donor.
- If the blood groups do not match, for example, if the donor’s blood group is ‘A’ and the recipient’s blood groupis is ‘B’, the recipient’s antibodies attach to the donor’s red blood cells and cause clumping (agglutnation).
- Errors that results in such Agglutnation can lead to blockage of small blood vessels and cause homolysis (rupture of red blood cells).
- Therefore, the blood of a donor has to be carefully matched with the blood of recipient before any blood transfusion. The donor’s compatibility is needed.
Blood groups | Antigens on RBCs | Antibodies in plasma | Donor’s group |
A | A | Anti- B | A,O |
B | B | Anti- A | B,O |
AB | A,B | nil | AB, A, B, O |
O | nil | Anti- A,B | O |
From the above mentioned table it is evident that blood group’O’ can be donated with any other blood group ansd hence ‘O’ group individuals are called universal donors’ Group ‘O’ fed blood cells lack A and B antigens, therefore the recipient’ antibodies cannot cause agglutination the donor’s RBCs. Persons with ‘AB’ group can accept blood from persons with AB as well as the other groups of blood. This is because blood group AB lacks anti- A and anti- B antibodies and thus cannot agglutinate donor’s red blood cells. Therefore, such persons are called ‘Universal recipients’.
Rh Grouping
- Another group of antigensfound on the red blood cells of most people is the Rh factor (Rh stands for rhesus monkey), in which these antigens were first discovered.
- It was discovered by Landsteiner and wiener..
- People who have these antigens are said to be Rh+ve, whereas those who do not have these are called Rh-ve
- An Rh+ve person, if exposed to Rh+ve blood, will form specific antibodies against the Rh antigens, Therefore, Rh group should also be matched before transfusion.
- A special case of Rh incompatibility (mismatching) has been observed between the Rh-ve blood of a pregnant mother with Rh+ve blood of the foetus. The Rh-ve mother is not usually exposed to the Rh antigen of the foetus during the first pregnancy as the foetal and maternal blood are normally kept well separated by the placenta barriers. However , at the time of birth of the first child, there is a possibility of exposure of the maternal blood to small amounts of the Rh+ve blood from the foetus, In such cases, the mother starts preparing antibodies against Rh antigen in her blood.
- These antibodies could cross the placental barriers in nsubsequent pregnancies and cause hemolysis of the Rh+ve red blood cells of the foetus. This could be fatal to the foetus or could cause severe anaemia and jaundice to the baby (HDN- jaemolytic disease of newly born). This condition is called erythroblastosis foetalis.
- Erythroblastosis foetalis can be prevented by injecting the Rh-ve mother with an antibody preparation (anti- Rh antibodies) against the Rh factor immediately after the birth of each Rh+ve baby.
Funfact:-
- ABO System: The most well-known blood group system is the ABO system, consisting of four main types: A, B, AB, and O.
- Universal Donor: People with type O negative blood are considered universal donors because their blood can be given to any blood type in an emergency.
- Universal Recipient: Individuals with type AB positive blood are known as universal recipients, as they can receive blood from any blood type.
- Rarest Blood Type: AB negative is the rarest blood type, found in less than 1% of the world’s population.
- Most Common Blood Type: O positive is the most common blood type globally.
- Rh Factor: The Rh factor is another important component, with Rh positive being more common than Rh negative.
- Genetic Inheritance: Your blood type is inherited from your parents, with each parent contributing one of two ABO genes.
- Blood Type and Personality: In Japan, blood types are often associated with personality traits, similar to how horoscopes are used in the West.
- Blood Type and Diet: The “Blood Type Diet” suggests that people should eat according to their blood type to improve health, although this is not scientifically proven.
- Blood Type Compatibility: Blood type compatibility is crucial for blood transfusions to prevent adverse reactions.
- Unique Antigens: Each blood type has specific antigens on the surface of red blood cells that determine compatibility.
- Erythroblastosis Fetalis: This condition occurs when an Rh-negative mother carries an Rh-positive baby, leading to complications if not treated.
- Bombay Blood Group: This is an extremely rare blood type where individuals lack the H antigen, making it difficult to find compatible donors.
- Blood Type Evolution: Different blood types evolved to protect against various diseases; for example, type O may provide resistance to malaria.
- Blood Types in Organ Transplants: Matching blood types is also essential for organ transplants to reduce the risk of rejection.
- Emergency Blood Transfusions: In extreme emergencies, type O negative blood is often used because of its universal donor status.
- Distribution Variation: Blood type distribution varies by ethnicity and geography, with some types more prevalent in certain regions.
- Blood Type and Pregnancy: Knowing the Rh factor is crucial during pregnancy to manage Rh incompatibility.
- Blood Type and Disease Risk: Some studies suggest that blood type may influence susceptibility to certain diseases, like type A being linked to a higher risk of stomach cancer.
- Blood Donation: Regular blood donation is vital to ensure a steady supply for emergencies and medical procedures, with type O negative donations being especially valuable.
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