Thromboxane B2 Synthesis in Human Platelets Induced by the Late Complement Components C5b-9

Abstract

Sublytic doses of purified C5b6, C7, C8 and C9 induce the release of thromboxane B₂ (TXB₂) in human platelets. In the present study, we attempted to analyze the signal by which C5b-9 triggers the prostanoid synthesis in platelets. TXB₂ release was accompanied by liberation of Ca⁺⁺ from intracellular stores. Influx of Ca⁺⁺ was not observed, indicating that C5b-9 did not form a channel large enough to permit passage of Ca⁺⁺ ions. Therefore, channel formation is apparently not required for cell stimulation.