Rabbit Platelet Injury by Soluble Antigen and Antibody

Several differences between EAC hemolysis and release of rabbit platelet amines by soluble antigen and antibody have been emphasized by contrasting the effects of some inhibitors on these two models of complement-mediated cell injury. Hemolysis of sensitized sheep cells in undiluted rabbit plasma is not inhibited by citrate. Immune platelet injury, in contrast, is completely inhibited by citrate, but only when this inhibitor is present before the interaction between antigen, antibody and complement. EAC hemolysis in undiluted rabbit plasma is not inhibited by tolsoyl arginine methyl ester (TAME) or acetyl tyrosine ethyl ester (AcTEE), whereas immune platelet injury is inhibited. Further, at plasma dilutions (10%) in which TAME (10 mM) does inhibit EAC hemolysis, the inhibitor must be added before or within 2.5 min after adding sensitized cells to plasma. In contrast, TAME inhibits immune injury to platelets even when added after 20 min preincubation of antigen, antibody and plasma (complement source), as long as it is present before addition of platelets. These observations add support to the concept that the details of complement action in producing EAC hemolysis on the one hand and platelet injury by soluble antigen and antibody on the other are quite different.