Differences and similarities between human and rabbit neutrophil granulocyte responses <i>in vitro</i>: the effects of zymosan‐activated plasma, phorbol myristate acetate and n‐formyl‐methionyl‐leucyl‐phenylalanine

Abstract

The amount of reactive oxygen intermediates (ROI) generated by activated polymorphonuclear neutrophils (PMN), as well as the closeness of contact between PMN and vessel wall, may determine whether PMN activators will induce the adult respiratory distress syndrome. We examined the ROI-generating and aggregating effects of zymosan activated plasma (ZAP), phorbol myristate acetate (PMA) and n-formyl-methionyl-leucyl-phenylalanine (FMLP), on isolated human and rabbit PMN. PMA, after a short lag phase, induced a large and long-lasting increase in ROI generation. The initial peak response was higher and more rapid in human than in rabbit cells. The reaction to FMLP occurred almost instantaneously, but was much weaker than that to PMA, and ROI generation returned to near baseline in less than 10 min. No species difference was seen. ZAP caused an FMLP-like ROI response in human cells, whereas no response was observed in rabbit PMN. PMN aggregation was induced by all three activators, most markedly by PMA. No species difference was detected for PMA; FMLP gave a stronger aggregation of rabbit than of human PMN, however, while the opposite was true for ZAP. In conclusion, ZAP was a potent stimulus for PMN aggregation, but had modest (or no) effects on the production of ROI. Marked differences between human and rabbit PMN responses were observed.