Secretion of IL-1 and H2O2 by human mononuclear cells in vitro

The secretion of hydrogen peroxide (H2O2) and interleukin-1 alpha (IL-1 alp ha) was evaluated during in vitro culturing of human monocytes. The oxidati ve metabolism and cytokine secretion were correlated to the cell distributi on (number of surface-associated cells), the DNA content and their integrit y, evaluated by lactate dehydrogenase (LDH) assay. The differentiation of c ultured monocytes was determined by the expression of CD14, 27E10 and RM3/1 . After 24 h cultivation, unstimulated cells had a low production of H2O2 a nd IL-1 alpha. A four-fold increase in the production of H2O2 was detected with 5 and 10 mu g/ml of lipopolysaccharide (LPS) and polystyrene (PS) part icles. PS particles induced a concentration-dependent increase in IL-1 alph a after 24 h. In contrast, cultivation for 48 h, did not result in any meas urable production of H2O2, irrespective of the type of stimulus. A decrease d viability of monocytes was shown after stimulation with PS particles in h igh concentrations. Our results indicate that the phenotype expression, adh esion, integrity and secretory pattern of human monocytes is dependent on t he culture time and the type and concentration of stimulus. (C) 2000 Elsevi er Science Ltd. All rights reserved.