The Effect of Platelet Membrane Antibodies on Aggregation and Release

S ummary . Human platelets were preincubated with Fab fiagments derived from two types of platelet antibodies: (1) antibody to whole platelet membranes, and (2) antibody to the major platelet membrane glycoprotein. Subsequently platelet aggregation and release of [¹⁴C]serotonin in response to adenosine diphosphate (ADP), adrenaline, thrombin, and collagen were evaluated. Following incubation with the anti-membrane antibody, significant inhibition of both aggregation and serotonin release was observed. The pattern of inhibition of ADP- and thrombin-induced aggregation and release differed from the inhibition noted after the addition of adrenaline or collagen. Treatment of platelets with the anti-membrane glycoprotein antibody had no effect on subsequent aggregation induced by ADP, adrenaline, thrombin or collagen.