CASE I. AUTOIMMUNE HEMOLYTIC ANEMIA (AIHA)
A. TYPE II AUTOIMMUNE REACTION
COMMENT:
AIHA in patients with SLE is usually due to the presence of warm reactive autoantibodies against the Rh antigen. As the autoantibody-coated erythrocytes pass through the spleen, phagocytes bearing Fc receptors remove some of the immunoglobulin on the cell surface along with some of the cell membrane, which subsequently reseals, causing the erythrocyte to take the form of spherocyte. Eventually, the erythrocyte is unable to be repaired and is removed from the circulation. If this occurs faster than new erythrocytes can be produced (normal life span of an erythrocyte is about 120 days) then anemia develops. The elevated indirect bilirubin (a measure of bilirubin before the liver has a chance to process it) is a result of the increased breakdown of hemoglobin.
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