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Recombinant human interleukin-1 beta primes human polymorphonuclear leukocytes for stimulus-induced myeloperoxidase
B Dularay1, C J Elson, S Clements-Jewery
1Medical School, University of Bristol, England.
Abstract:
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.
Insights
Recombinant human Interleukin-1 beta enhances immune cell degranulation. This finding suggests IL-1 beta may boost polymorphonuclear leukocyte activity in inflammatory conditions like rheumatoid joints.
Area of Science:
- Immunology
- Cell Biology
Background:
- Polymorphonuclear leukocytes (PMNs) are key immune cells involved in inflammatory responses.
- Granule exocytosis and oxidative responses are critical functions of PMNs.
- Interleukin-1 (IL-1) beta is a pro-inflammatory cytokine implicated in various diseases.
Purpose of the Study:
- To investigate the effect of recombinant human Interleukin-1 (rhIL-1) beta on PMN degranulation and oxidative response.
- To determine if rhIL-1 beta primes PMNs for enhanced responses to stimuli.
Main Methods:
- Human PMNs were incubated with varying concentrations of rhIL-1 beta.
- PMNs were subsequently stimulated with heat-aggregated IgG (Hagg) or N-formyl-methionyl leucylphenylalanine (FMLP).
- Myeloperoxidase (MPO) release was measured to quantify degranulation; oxidative response was also assessed.
Main Results:
- Low concentrations of Hagg or FMLP, ineffective alone, induced significant degranulation in rhIL-1 beta-primed PMNs.
- The enhancement of degranulation was dose-dependent on rhIL-1 beta concentration and incubation time.
- rhIL-1 beta did not directly stimulate or enhance the oxidative burst in PMNs.
Conclusions:
- rhIL-1 beta significantly potentiates stimulus-induced granule exocytosis from human PMNs.
- IL-1 beta may enhance PMN inflammatory function in rheumatoid joints by promoting degranulation, without affecting their oxidative response.