Potentiation of Neutrophil Function by Recombinant DNA‐Produced Interleukin 1a

The effect of interleukin la (IL-la) produced by E. coli-derived recombinant DNA was evaluated on various parameters of human neutrophil function. IL-la alone stimulated neutrophil hydrogen peroxide production in a dose-dependent manner, but the rate was much lower than that of opsonized zymoasn. IL-la induced release of specific granule contents, but not azurophilic granule contents. Cytochalasin B did not augment the rate of release. IL-la was chemotactic for neutrophils at the optimal concentrations of 0.110 ng/ml. Pretreatment of the neutrophils with IL-la augmented neutrophil oxygen radical production induced by opsonized zymosan, and this synergistic effect was evident as early as 10 mm after IL-la was added to the neutrophil culture. Phagocytosis of opsonized particles by neutrophils, and degranulation induced by opsonized zymosan were also enhanced by IL-la in a dose-dependent manner. The present results suggest that IL-la is weak as a direct activator of neutrophil function and that IL-la in vivo may augment the response of neutrophils to other stimulators such as foreign bodies.