Recombinant human interleukin-1 beta primes human polymorphonuclear leukocytes for stimulus-induced myeloperoxidase...

Recombinant human Interleukin-1 (rhIL-1) beta was found to enhance stimulus-induced granule exocytosis from human polymorphonuclear leukocytes (PMNs). PMNs were incubated with rhIL-1 beta and then stimulated with either heat-aggregated IgG (Hagg) or N-formyl-methionyl leucylphenylalanine (FMLP). The release of the azurophil enzyme myeloperoxidase (MPO) was measured. Low concentrations of stimuli (10 micrograms/ml Hagg, 2.5 X 10(-9) M FMLP) did not stimulate degranulation in the absence of rhIL-1 beta. However, such concentrations elicited marked degranulation from PMNs preincubated with rhIL-1 beta (0.2-100 ng/ml). The enhancement of degranulation was dependent on the concentration of rhIL-1 beta employed and on the period of incubation. In other experiments, the effect of rhIL-1 beta on the PMN oxidative response was determined. rhIL-1 beta 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-1 beta may potentiate PMN degranulation, but not their oxidative response.