Activation of the human neutrophil respiratory burst with zymosan-activated serum

Zymosan-activated serum ( ZAS ) stimulated a time- and concentration-dependent generation of superoxide anion (O-2) by human neutrophils. O-2 production was rapid with maximum generation occurring 2 minutes after cell exposure to ZAS . O-2 generation is markedly reduced if cells are not preincubated with cytochalasin B prior to contact with ZAS . The amount of O-2 produced by ZAS stimulated neutrophils was enhanced in the presence of extra-cellular calcium. However, the intracellular calcium antagonist, 8-(N,N-diethylamino)-octyl-(3,4,5-trimethoxy) benzoate hydrochloride (TMB-8), caused a dose-related inhibition of ZAS -elicited O-2 production. Neutrophils pretreated with ZAS were desensitized to the subsequent exposure to this stimulus. The fact that pretreatment of neutrophils with ZAS did not diminish the capacity of these cells to generate O-2 in response to 1-O-hexadecyl/octadecyl-2-O-acetyl-sn-glyceryl-3-phosphorylcholine (AGEPC),N-formyl-methionyl-leucyl-phenylalanine (FMLP) or 5(5),12(R)-dihydroxy-6,14-cis-8,10-trans-eicosatetraenoic acid (LTB4), demonstrates the stimulus specific nature of ZAS -induced desensitization. Thus, ZAS , which contains the complement-derived neutrophil activator, C5a, a naturally occurring phlogistic mediator, represents a relevant probe for investigating neutrophil function.