[The capacity of Yersinia pestis toxin to decrease the functional response of human thrombocytes to stimulation by hormones].

Yersinia pestis toxin (fraction II by E. Baker) (YPT) inhibited the aggregation of human platelets as well as elevation of [Ca2+], induced by different agonists (ADP, PAF, Thrombin). Agonist-induced Ca2+ mobilization and Ca2+ influx were dose-dependently inhibited by the toxin. The effect was rapid, developing during the first minute of incubation with toxin. In contrast to murine lethal protein (MLP), the platelet-inhibiting activity was thermostable and was eliminated in the course of MLA purification from YPT. These data indicate that Yersinia pestis component, unlike MLP, could influence the Ca(2+)-dependent processes in human platelets.