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Small glycoproteins found on both hematopoietic and non-hematopoietic cells. CD59 restricts the cytolytic activity of homologous complement by binding to C8 and C9 and blocking the assembly of the membrane attack complex. (From Barclay et al., The Leukocyte Antigen FactsBook, 1993, p234)

A substance that develops in serum on standing which protects red blood corpuscles against hemolysis. It may be increased by heating to 60 C., be taken up by non-sensitized cells and extracted by various fat solvents such as ether.