Reevaluation of the presence of the major antigen Ca++ complex in Bernard-Soulier syndrome platelets. Elastase degradation of the complex in Bernard-Soulier syndrome platelet preparations.

Crossed immunoelectrophoresis of human platelet membranes reveals a major antigen GPIIb-GPIIIa-Ca++ complex which is absent to decreased in Glanzmann's thrombasthenia. In our initial report, we also noted its absence in two patients with Bernard-Soulier syndrome associated with the presence of two neoantigens, and postulated that this may be due to endogenous proteolysis. It now appears that this observation is due to exogenous proteolysis from granulocyte-elastase contamination in the platelet membrane preparation. Purified elastase is capable of degrading the major antigen-Ca++ complex, particularly in its dissociated form, to the pattern initially reported for Bernard-Soulier platelets. Of particular interest is the observation that the elastase-degraded dissociated complex can be reassociated in the presence of Ca++. This indicates that the elastase-sensitive antigenic determinants recognized by the rabbit anti-human platelet membrane antibody are not required for the bonds which reassociate the complex.