The in vivo effect of leukotriene B4 on polymorphonuclear leukocytes and the microcirculation. Comparison with activated complement (C5a des Arg) and enhancement by prostaglandin E2.

The effect of synthetic leukotriene B4 (LTB4) on chemotaxis in vivo (51Cr-polymorphonuclear leukocyte [PMN] accumulation) was examined and its potency compared with that of C5a des Arg-containing zymosan-activated plasma (ZAP). On a molar basis the amount of C5a des Arg calculated to be in our preparation of ZAP was found to be up to approximately 80 times more potent than LTB4, although in vitro the two chemotaxins have been reported to be about equipotent. ZAP is more representative of what may happen in vivo than its principal constituent C5a des Arg, but for a more precise comparison the purified and isolated peptide will have to be compared with synthetic LTB4.