Recombinant Human Interleukin‐1 Beta Primes Human Polymorphonuclear Leukocytes for Stimulus‐Induced Myeloperoxidase Release

Recombinant human Interleukin‐1 (rhlL‐1) β was found to enhance stimulus‐induced granule exocytosis from human polymorphonuclear leukocytes (PMNs). PMNs were incubated with rhlL‐1β and then stimulated with either heat‐aggregated IgG (Hagg) or N‐formyhmethionyl leucylphenylalanine (FMLP). The release of the azurophil enzyme myeloperoxidase (MPO) was measured. Low concentrations of stimuli (10 μg/ml Hagg, 2.5 x 10‐9 M FMLP) did not stimulate degranulation in the absence of rhlL‐1β. However, such concentrations elicited marked degranulation from PMNs preincubated with rhlL‐1β (0.2‐100 ng/ml). The enhancement of degranulation was dependent on the concentration of rhIL‐1β employed and on the period of incubation. In other experiments, the effect of rhlL‐1β on the PMN oxidative response was determined. rhlL‐1β did not directly stimulate the production of superoxide anions or enhance the oxidative response to Hagg or FMLP. It is suggested that in rheumatoid joints, IL‐1β may potentiate PMN degranulation, but not their oxidative response.