Platelet Reactions and Immune Processes

Abstract

SummaryWe have studied the effect of chymotrypsin substrates and inhibitors on the aggregation of human platelets by collagen, latex, and epinephrine :1. We have found that platelet aggregation was inhibited by most chymotrypsin substrates and inhibitors which we studied.2. In general, there was a positive correlation between the effectiveness of the compounds as chymotrypsin substrates or inhibitors on one hand, and as platelet aggregation inhibitors on the other hand. However aromatic amino acid derivatives acetylated on the α-amine group were much less effective with platelets than they are with chymotrypsin.3. Chymotrypsin substrates and inhibitors also inhibit the anaphylactic release of histamine. The view is presented that the platelet release reaction and the mast cell release reaction have several common biological and biochemical features.4. The possible role of platelet esterases in platelet thrombogenetic reactions is discussed in the light of the present knowledge of the role of cell bound esterase in several inflammatory or immune cellular processes.