Differential in vitro effects of physiological and atmospheric oxygen tension on normal human peripheral blood mononuclear cell proliferation, cytokine and immunoglobulin production

Since the early work of Mischell & Dutton (Science 153, 1004-1008, 1966), it has been recognized that certain lymphocyte cultures are exquisitely sensitive to the harsh effects of atmospheric oxygen tension. The influence of oxygen partial pressure (pO(2)) on normal human peripheral blood mononuclear cell (PBMC) phenotype, proliferative ability, cytokine, immunoglobulin production, and redox status was examined by culturing PBMC under ambient oxygen (high pO(2)) or a more physiological pO(2) (5% O-2; low pO(2)). Low pO(2) conditions promoted a significant increase in overall viable PBMC number and enhanced Concanavalin A (Con A)- or pokeweed mitogen (PWM)-stimulated PBMC proliferation by approximately 30% and 50%, respectively. No differential pO(2) effects were apparent on phytohemagglutinin (PHA)- or staphylococcal enterotoxin B (SEB)-induced proliferation. Both resting and Con A-stimulated lymphocytes incubated for 24 h under high pO(2) had a greater baseline carboxy-2'7'-dichlorofluorescin (C-DCF) fluorescence, and were less able to quench the effect of H2O2 treatment compared to lymphocytes cultured under low pO(2) conditions. Supernatant gamma-IFN, IL-2, and IL-4 concentrations were elevated 50-65% when PBMC were stimulated with Con A for 24 h under low pO(2); however, lipopolysaccharide (LPS)-stimulated IL-1 beta production was reduced by over 75%. PWM-stimulated IgM production by PBMC was significantly reduced in day 7 cultures incubated under low pO(2), whereas IgG and IgA production remained relatively unaltered. Immunophenotyping analyses did not reveal any significant alterations in cell subset or marker distribution at the time points examined; however, an interesting trend of increased CD69 expression was observed for Con A-stimulated PBMC incubated under low pO(2). These results demonstrate that O-2 isa critical parameter for the in vitro culture of lymphocytes, and suggests that varying pO(2) may differentially alter PBMC functionality. (C) 1997 International Society for Immunopharmacology.