The page below is a sample from the LabCE course Transfusion Reactions. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

Learn more about Transfusion Reactions (online CE course) »
How to Subscribe
MLS & MLT Comprehensive CE Package
Includes 94 CE courses, most popular
$95 Add to cart
Pick Your Courses
Up to 8 CE hours
$50 Add to cart
Individual course$20 Add to cart

In Vivo Red Cell Destruction

Important events that occur in an immune-mediated hemolytic transfusion reaction (HTR) include:

  • Antibody binding to red blood cells
    • Antibodies may be either IgM or IgG.
    • IgM antibodies activate complement and lead to intravascular hemolysis where free hemoglobin is released into the plasma.
    • IgG antibodies rarely activate complement but they are often involved in effecting phagocytosis.
    • The concentration of the antibody is directly related to the severity of the HTR.
  • Activation of complement
    • The end result of complement activation is red cell lysis.
  • Activation of mononuclear phagocytes and cytokines
    • Sensitized red cells are removed from circulation by mononuclear phagocytes. Macrophages in the spleen and Kupffner cells in the liver are active in this process.
  • Activation of coagulation
    • Antibody-antigen complexes may initiate coagulation and cause disseminated intravascular coagulation (DIC).
  • Shock and Renal Failure

Hemolysis can be intravascular or extravascular. In intravascular hemolysis, free hemoglobin, RBC stroma, and intracellular enzymes are released into the blood stream. This results in hemoglobinemia and hemoglobinuria, which can lead to kidney damage. In extravascular hemolysis, there is no release of free hemoglobin. Sensitized red cells are removed from the circulation by the monocytes and macrophages in the reticuloendothelial system.