Inhibitory effect of interleukin-8 on the secretion of platelet-activating factor acetylhydrolase by human decidual macrophages.

Objective: To determine whether interleukin-8 (IL-8) regulates platelet-activating factor acetylhydrolase (PAF-AH) secretion by decidual cells in vitro.

Methods: Decidual macrophages were obtained from human term decidual tissue by enzymic digestion and Ficoll-Paque centrifugation. The effect of IL-8 and phorbol esters on the secretion of PAF-acetylhydrolase by these cells was examined.

Results: IL-8 inhibited PAF-AH secretion by decidual macrophages in a dose-dependent manner. The inhibition was reversed partially by antibodies against tumor necrosis factor-alpha and IL-1 beta. IL-8-induced inhibition was blocked partially by the protein kinase C (PKC) inhibitors, sphingosine, and H-7 1-(5-isoquinoline sulfonyl)-2-methylpiperazine. A PKC activator, 12-O-tetradecanoyl phorbol 13-acetate, decreased PAF-AH secretion.

Conclusion: IL-8 may increase the PAF concentration in the decidua via its inhibitory effect on PAF-AH secretion by decidual macrophages. IL-8-induced inhibition of enzyme secretion may have been mediated in part by PKC-dependent signal transduction.