The effects of an ECF-A and formyl methionyl chemotactic peptides on oxidative metabolism of human eosinophils and neutrophils.

An ECF-A tetrapeptide (Val-Gly-Ser-Glu) and the synthetic bacterial analogue, formyl Met-Leu-Phe (agents previously recognized to be chemotactic and to enhance complement receptors on human eosinophils and neutrophils), were tested for their capacity to evoke a spontaneous burst of light emission (chemiluminescence), and to affect oxygen-consuming reactions induced by contact with serum-treated zymosan (STZ). Superoxide anion (O-2) production by neutrophils induced by STZ was significantly enhanced in both a time- and concentration-dependent fashion by F-Met-Leu-Phe, and to a lesser extent, by F-Met-Met-Phe. The dipeptide F-Met-Phe and unformylated Met-Leu-Phe were inactive. In addition, significant enhancement of eosinophil O-2 generation, by the valyl- ECF-A tetrapeptide was demonstrable and, in addition, this peptide appeared to have an inhibitory effect on neutrophil superoxide anion generation. Eosinophils and neutrophils both produced a burst of chemiluminescence when treated with F-Met-Leu-Phe. With both cell types the magnitude of the responses was similar although with eosinophils peak activity occurred within 60 sec as compared to 2-6 min for neutrophils. No chemiluminescent response was achieved with the valyl- ECF-A tetrapeptide using either cell type. These experiments (1) suggest that ECF-A and formyl methionyl peptides amplify reactions associated with the respiratory burst of eosinophils and neutrophils respectively, and (2) support the view that the generally greater metabolic activity of eosinophils may be related to the special role that this cell may play in the killing of helminthic parasites.