Platelet-activating factor (PAF) modulates peritoneal mouse macrophage infection by Leishmania amazonensis

The effects of platelet-activating factor (PAF) on the infection of periton eal mouse macrophages by Leishmania amazonensis were investigated. Prior to the infection, the parasites and/or the macrophages were treated with PAF and/or one of the following modulators: WEB 2086 (PAF antagonist), and the modulators of protein kinase C, phorbol-12-myristate-13-acetate (PMA), and sphingosine. The infection was inhibited when the macrophages or both the p arasites and the macrophages were treated with PAF, but stimulated by PAF-t reated parasites. WEB 2086 abrogated PAF effects in both systems, The infec tion was stimulated when the macrophages were treated with sphingosine plus PAF, but inhibited when the macrophages were treated with sphingosine and the parasites with sphingosine plus PAF. The infection was inhibited by sph ingosine-treated parasites, either in the presence or in the absence of PAF . Leishmania amazonensis-macrophage infection was inhibited by PMA in all s ystems tested.