Blood Groups and Transfusion Basics

Blood Groups and Blood Transfusion

• Blood transfusions weren't possible until Karl Landsteiner identified the major human blood groups (A, B, AB, and O) in 1901. This work earned him the Nobel Prize.
• Currently, 31 different genes are known to affect the surface features of red blood cells (RBCs), determining blood type compatibility.
• The primary blood group systems are ABO and Rh.
• ABO blood groups are defined by specific inherited molecules (antigens) on the surface of RBCs.

ABO Blood Groups

• Antigens are chemicals that trigger the production of antibodies.
• Antibodies are proteins that react against specific antigens.
• ABO blood types are categorized based on the presence or absence of antigens A and B on RBCs.
• Blood type A has antigen A and antibodies against B.
• Blood type B has antigen B and antibodies against A.
• Blood type AB has both antigens A and B and no antibodies.
• Blood type O has neither antigen A nor B and has antibodies against both A and B.
• Antibodies in the ABO system typically appear in babies within the first six months after birth.

Rh Blood Group

• The Rh blood group was named after the Rhesus monkey.
• The Rh system includes several Rh antigens (such as Cc, Dd, and Ee).
• Rh-positive individuals possess the antigen D.
• Rh-negative individuals lack the antigen D.
• Rh incompatibility can lead to erythroblastosis fetalis (hemolytic disease of the newborn) in subsequent pregnancies if the mother is Rh-negative and the fetus is Rh-positive.

Importance of Blood Groups

• Blood groups play a role in disease association. Duodenal ulcers are more common in blood type O than in blood types A or B. Tumors of the salivary glands, stomach, and pancreas are more prevalent in blood type A than in blood type O.

Landsteiner's Law

• If an agglutinogen (antigen) is present on the RBCs, the corresponding agglutinin (antibody) must be absent in the plasma.
• If an agglutinogen (antigen) is absent on the RBCs, the corresponding agglutinin (antibody) must be present in the plasma.

Blood Transfusion

• Blood grouping and cross-matching is essential for safe transfusions.
  • Donor's RBCs + Recipient's plasma (major cross-matching)
  • Recipient's RBCs + Donor's plasma (minor cross-matching)
• Blood type O is the universal donor, as it lacks antigens A and B.
• Blood type AB is the universal recipient, as it has neither anti-A nor anti-B antibodies.

Complications of Blood Transfusion

• Mismatched transfusions can lead to fatal hemolytic reactions.
• Other complications include rapid hemolysis, jaundice, renal tubular damage, circulatory overload, hemosiderosis, electrolyte imbalances, and transmission of diseases (e.g., hepatitis B/C, AIDS).

Erythroblastosis Fetalis

• This is hemolytic disease of the newborn, often caused by Rh incompatibility.
• Rh-negative mothers carrying Rh-positive fetuses can develop antibodies.
• Maternal antibodies cross the placenta and attack fetal red blood cells.
• Clinical symptoms include edema, jaundice, and anemia.

Treatment and Prevention of Erythroblastosis Fetalis

• Treatment includes exchange blood transfusions.
• Prevention involves administering anti-D immunoglobulin to Rh-negative mothers early in pregnancy to prevent antibody formation.

Blood Groups in Local Population

• The percentages of blood types (O+, A+, B+, AB+, O-, A-, B-, and AB-) in a particular population are provided (e.g. O+, 48%; A+, 24%; etc.)