BLOOD GROUP
BLOOD GROUP: A blood type or blood group is the classification of blood on the basis of the presence or absence of inherited antigens (proteins, carbohydrates, glycoproteins, or glycolipids) on the surface of RBCs.
Significance of Blood Grouping
- Essential for successful blood transfusion (donor and recipient).
- Important to resolve paternity disputes and medico-legal cases.
- Significant in diagnosis of blood grouping related diseases (haemolytic disease).
Blood Grouping Systems
- Classical ABO blood grouping system
- Rhesus (Rh) blood grouping system
- MNS blood grouping system
- P blood grouping system
First two are major systems (more prevalent, cause severe transfusion reactions); last two are minor systems (small proportion of population, produce minute transfusion reactions).
ABO BLOOD GROUP
The ABO blood group system was proposed by Austrian pathologist Karl Landsteiner in 1901. It is based on A and B antigens on RBCs surface and circulating antibodies in plasma.
Four Types of ABO Blood Groups
- Type A: Protein A (antigen) + antibodies for protein B
- Type B: Protein B (antigen) + antibodies for protein A
- Type AB: Proteins A and B (antigens) + no antibodies
- Type O: No proteins (antigens) + both A and B antibodies
| Blood Group | Antigen | Antibody | As Donor | As Recipient |
|---|---|---|---|---|
| A | Antigen A | Makes anti-B | A and AB | A and O |
| B | Antigen B | Makes anti-A | B and AB | B and O |
| AB | Antigens A and B | Makes neither anti-A nor anti-B | AB only | All groups (Universal Recipient) |
| O | Neither A nor B antigen | Makes both anti-A and anti-B | All groups (Universal Donor) | O only |
Universal Donor: Type O blood group (can donate blood to anyone).
Universal Recipient: Type AB blood group (can receive blood from any type).
Rh BLOOD GROUP
First detected in Rhesus monkey. About 97% of Indian population are Rh positive (presence of Rh antigens). Generally, no anti-Rh antibodies are found in blood plasma naturally; they are produced by immune system when an Rh⁻ person receives Rh⁺ blood.
Rh Incompatibility and Erythroblastosis Foetalis
- Mother Rh⁻ and father Rh⁺ → baby may inherit Rh⁺ allele from father.
- During pregnancy, some foetal blood passes to mother via placenta.
- Mother’s blood produces Rh⁺ antibodies (first pregnancy: low concentration → no complications).
- In second Rh⁺ child, mother’s antibodies cross placenta and cause clumping of foetal RBCs → Erythroblastosis Foetalis (can cause foetal death).
Prevention (RhoGAM)
Within three days after the birth of her first Rh⁺ child, an Rh⁻ mother should be administered RhoGAM to eliminate any Rh⁺ antibodies from her blood, preventing antibody formation against future Rh⁺ foetuses.
IMPORTANCE OF BLOOD GROUPING
- In Blood Transfusions: Incompatible transfusion can cause IV clumping and fatal reactions.
- During Pregnancy: Rh incompatibility between mother and foetus can lead to medical issues; special drugs prevent antibody production.
- Organ and Tissue Transplants: Donor organs/tissues must be compatible with recipient’s blood type to avoid immune rejection.
- Emergency Medical Care: Knowing blood type ensures safe and effective transfusion in emergencies.
- Forensic Medicine: Helps identify possible blood types in crimes, accidents, or other cases.
- Paternity Testing: Provides insight into possibility of biological fatherhood.
- Genetic Research and Anthropology: Offers comprehensions into human hereditary variety and migration patterns.
- Medical Research and Disease Association: Specific blood groups are linked to several illnesses; helps advance medical research.
- Blood Donation and Availability: Ensures donated blood products are accurately labeled and matched to recipients.
