Blood Typing and Transfusion Lecture 21 PDF

blood 2 - lecture 21 Created @December 10, 2024 10:12 PM Class immunology blood and stem cells Blood Typing and Transfusion Historical Background Karl Landsteiner's work led to the discovery of the ABO and...

blood 2 - lecture 21 Created @December 10, 2024 10:12 PM Class immunology blood and stem cells Blood Typing and Transfusion Historical Background Karl Landsteiner's work led to the discovery of the ABO and Rhesus (Rh) blood classification systems. Before these systems, blood transfusions were inconsistent and often dangerous. ABO Blood Group System Main Blood Types: A, B, AB, and O. Each type is further classified as positive (+) or negative (-), creating a total of 8 blood types: A+, A-, B+, B-, AB+, AB-, O+, O-. Blood type is determined by the presence or absence of A and/or B antigens on red blood cells (RBCs): Type A: Has A antigen. Type B: Has B antigen. Type AB: Has both A and B antigens. Type O: Has neither A nor B antigens. Immune Response and Compatibility Antigens: Markers on cell surfaces that identify cells as self or foreign. Antibodies: Produced by B-lymphocytes to target specific foreign antigens. blood 2 - lecture 21 1  Each blood type produces antibodies against non-self antigens: Type A: Anti-B antibodies. Type B: Anti-A antibodies. Type AB: No antibodies (Universal recipient). Type O: Anti-A and Anti-B antibodies (Universal donor). Incompatibility Reaction: When the recipient’s antibodies attack donor RBCs, it causes intravascular hemolysis (destruction of RBCs), leading to severe complications. Donor antibodies against the recipient's antigens are usually negligible due to dilution. Rhesus (Rh) System Determines the presence of the Rhesus antigen (Rh) on RBCs: Rh+: Rhesus antigen is present. Rh-: Rhesus antigen is absent. Unlike the ABO system, Rh-negative individuals do not naturally have anti-Rh antibodies. These are produced only upon exposure to Rh-positive blood (e.g., through transfusion or pregnancy). Hemolytic Disease of the Newborn (HDN) Occurs when an Rh-negative mother gives birth to an Rh-positive baby. Maternal exposure to fetal Rh-positive blood during childbirth leads to the formation of anti-Rh antibodies. These antibodies can attack RBCs in future Rh-positive pregnancies. Prevention: Administer synthetic anti-Rh antibodies to the mother immediately after childbirth to prevent sensitization. blood 2 - lecture 21 2  Blood Transfusion Compatibility 1. Universal Donors and Recipients: O-negative: Universal donor; lacks A, B, and Rh antigens. AB-positive: Universal recipient; lacks antibodies against A, B, or Rh antigens. 2. Rules: Donor RBCs must not have antigens that the recipient's antibodies can target. Donor antibodies against recipient antigens are less significant but still monitored. Practical Applications in Blood Typing Testing: Blood is mixed with anti-A and anti-B antibodies to identify agglutination (clumping) and determine blood type. Emergency Transfusions: O-negative blood is used to save time as it is universally compatible. Prevalence of Blood Types Rhesus Positive (Rh+): Over 80% of the population. Most Common Blood Type: O-positive. Least Common Blood Type: AB-negative. Variations by Population: Blood type distribution varies by ethnicity: Example: B-positive is more common in the Indian population (~30%) than in the UK Caucasian population (~8%). blood 2 - lecture 21 3