New functions for platelets and their pathological implications.

We have recently demonstrated in Schistosoma mansoni infection that rat and human platelets could very efficiently kill parasite larvae, both in vivo and in vitro. The study of this IgE-dependent platelet effector function has led us to several subsequent findings. They concern: (1) the existence of a specific receptor for IgE on the platelet surface; (2) its close association with a platelet membrane glycoprotein of essential functional importance, the GPIIb-IIIa complex; (3) the observation, in extrinsic allergic asthma, of an allergen-specific IgE-dependent platelet activation; (4) the identification, in aspirin-sensitive asthma, of a similar, but non-IgE-dependent, platelet activation selectively induced by cyclo-oxygenase inhibitors, and prevented by salicylate. Beyond their implication in anti-parasite immunity, these findings provide a basis for new insights on the participation of platelets in disease.