Actions of platelet activating factor (PAF) homologues and their combinations on neutrophil chemokinesis and cutaneous inflammatory responses in man

Abstract

The inflammatory actions of synthetic C16:0 and C18:0 platelet activating factor (PAF) homologues, both alone and in combination, have been compared in an in vitro human neutrophil chemokinesis assay and by intradermal injection in human skin. In the chemokinesis assay, the maximum distance moved by neutrophils in the presence of C 18: 0 PAF was significantly greater than that seen with the C16:0 compound. A mixture of C16: 0 and C18:0 PAFs in a ratio of 1: 9 appeared to be more active than in a ratio of 3:1. Intradermal injection of the C16:0 and C18:0 PAF homologues induced dose-dependent increases in weal volume and flare area responses which were not significantly different. Combination of these phospholipids in a ratio of 3: 1 or 1: 9 of C16: 0: C18: 0 did not significantly alter the dose response curves. Thus, changes in the chain length of the alkyl substituent of synthetic PAF homologues and combination of these homologues, in ratios found in vivo or formed by leukocytes in vitro, did not alter the cutaneous inflammatory responses to PAF in man. The C 18: 0 homologue was, however, more active as a human neutrophil chemoattractant in vitro. © 1988.