Cell-cell interactions between platelets, macrophages, eosinophils and natural killer cells in thromboxane A2...

Biosynthesis of thromboxane A2 (TxA2) during cell-cell interactions between platelets and alveolar macrophages, eosinophils and natural killer cells from guinea pigs has been investigated. The stimulation of platelets incubated with varying numbers of macrophages or eosinophils or NK cells with 5 microM ionophore A23187 has induced an increase of TxA2 synthesis in comparison to the sum of TxA2 production by each cell population stimulated alone. These results suggest that transcellular biosynthesis of TxA2 or cell cooperation occurred between platelets and the other cell population studied, which could correspond to cell-cell interactions of type IA and/or type III, according to the classification proposed by Marcus ((1986) Prog. Hemost. Thromb. 28, 127-42). When varying concentrations of platelets were incubated with the supernatant of cells previously stimulated with the ionophore A23187, an enhancement of TxA2 release was also observed. However, the supernatant of platelets stimulated with the ionophore A23187 did not induce a significant increase of TxA2 synthesis by the other cell populations. It is suggested that the biosynthesis of TxA2 during cell-cell interactions could account for the large amount recovered in biological fluid in various pathological conditions such as inflammatory and hypersensitivity reactions.