Pathophys Test 2

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Pathophys Test 2
2010-03-31 22:56:57
ABO Antigens and Antibodies

ABO Antigens and Antibodies
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  1. ABO antigens (p.24)
    Located on membranes of many cells of the body (RBCs, epithelial cells, endothelial cells)
  2. ABO system – extremely important in blood transfusions and organ transplantation
    • Antigens’ wide distribution
    • Presence of preformed antigens
    • Individuals normally have antibodies to ABO antigens NOT found in their own tissue cells or RBCs
    • - Result of cross-reactions with carbohydrate determinants of environmental bacteria
    • - When one comes in contact with bacterial antigens (or proteins), he or she forms antibodies that react to “similar” antigens on RBCs
  3. Rh Antigens
    • There are about 25 components of Rh blood group, but only cde/CDE alleles play significant role in Rh incompatibility reactions
    • Unlike ABO system, antibodies are not formed until an Rh-negative person receives blood from Rh-positive donor
  4. What is the purpose of Rh-immune globulins like Rhogam or Gamulin Rh – meaning how do they prevent sensitization of mother’s immune system against fetal RBCs? (p.24)
    • Anti-D-globulins given on exposure to Rh-positive blood or prophylactically
    • Anti-D antibodies cover (mask) antigenic sites on fetal RBCs and are then removed by scavenger cells
    • May prevent sensitization of mother’s immune system to fetal Rh-antigens
  5. Review blood group compatibility (p.24)