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, 196 6), it has been recognized that certain lymphocyte cultures are exquis itely sensitive to the harsh effects of atmospheric oxygen tension. Th e influence of oxygen partial pressure (pO(2)) on normal human periphe ral blood mononuclear cell (PBMC) phenotype, proliferative ability, cy tokine, immunoglobulin production, and redox status was examined by cu lturing 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 significan t increase in overall viable PBMC number and enhanced Concanavalin A ( Con A)- or pokeweed mitogen (PWM)-stimulated PBMC proliferation by app roximately 30% and 50%, respectively. No differential pO(2) effects we re apparent on phytohemagglutinin (PHA)- or staphylococcal enterotoxin B (SEB)-induced proliferation. Both resting and Con A-stimulated lymp hocytes incubated for 24 h under high pO(2) had a greater baseline car boxy-2'7'-dichlorofluorescin (C-DCF) fluorescence, and were less able to quench the effect of H2O2 treatment compared to lymphocytes culture d under low pO(2) conditions. Supernatant gamma-IFN, IL-2, and IL-4 co ncentrations were elevated 50-65% when PBMC were stimulated with Con A for 24 h under low pO(2); however, lipopolysaccharide (LPS)-stimulate d IL-1 beta production was reduced by over 75%. PWM-stimulated IgM pro duction by PBMC was significantly reduced in day 7 cultures incubated under low pO(2), whereas IgG and IgA production remained relatively un altered. Immunophenotyping analyses did not reveal any significant alt erations in cell subset or marker distribution at the time points exam ined; however, an interesting trend of increased CD69 expression was o bserved for Con A-stimulated PBMC incubated under low pO(2). These res ults demonstrate that O-2 isa critical parameter for the in vitro cult ure of lymphocytes, and suggests that varying pO(2) may differentially alter PBMC functionality. (C) 1997 International Society for Immunoph armacology.