DIFFERENTIAL SENSITIVITIES TO HYPERBARIC-OXYGEN OF LYMPHOCYTE SUBPOPULATIONS OF NORMAL AND AUTOIMMUNE MICE

We studied the effect of exposure to hyperbaric oxygen (HBO): 2.8 atm absolute 100% oxygen for 4 h daily over 3-7 days, on the immune system of normal (BALB/c and MRL-+/+) and autoimmune MRL-lpr/lpr) mice. In H BO exposed BALB/c mice, we observed a remarkable decrease in the cell population of the spleen and thymus. We found that the sensitivity to HBO varied among subpopulations of lymphocytes. For example, CD4(+)CD8 (+) double positive cells in the thymus and B220(+) B cells in the spl een were more sensitive than CD4(+) or CD8(+) single positive T cells in the thymus, and Thy-1(+) T cells in the spleen, respectively. Accor dingly, despite the decrease in total cell number in the spleen, the p roliferative response of T cells from the spleen to Con A was not impa ired in the HBO exposed mice. Exposure of MRL-lpr/lpr mice to HBO caus ed a marked reduction of weight and cell population of the otherwise e nlarged spleen and lymph nodes, and amongst others of percentages of B 220(+)Thy-1(+) double positive abnormal cells. These results suggest t he HBO therapy may be applicable for the treatment of some autoimmune diseases. (C) 1997 Elsevier Science B.V.