[abstract] EFFECTS OF DEEP SATURATION DIVING ON THE LYMPHOCYTE SUBSET CHANGE

Abstract

BACKGROUND: We have previously reported that remarkable decrease in CD4+ fraction of T lymphocytes (helper T cells) occurred during deep saturation diving. High pressure rather than HBO was suspected as a main candidate inducing immunosuppression. In the present study, we focused on the fractions of natural killer (NK) cells and (/( T cells as well as helper T cells, and analyzed the immunosuppressive effect of deep saturation diving. METHODS: A 400m saturation diving simulation was carried out in a diving simulator at Undersea Medical Center in 1996. Blood samples were collected from five healthy divers, on Days 2 (before diving), 4 (400m), 8 (400m), 12 (400m), 19 (250m), 25 (110m), and 30 (after surfacing). Samples were stained with fluorescent monoclonal antibodies (Leu4/Leu12, Leu3a/Leu2a, Leu7/Leu2a, Leu4/Leu11c+19, anti-TCR-(/(-1). Measurement of lymphocyte subsets was performed with a FACSCalibur flowcytometer and data were analyzed with CELLQuest software. RESULTS: The fraction of helper T (leu3a+) cells decreased from 42.3+/-6.6percent (before diving) to 32.0+/-2.8percent (on Day 8). The CD4:CD8 ratio was increasingly suppressed with depth and reached 0.84 (before diving = 1.38) on Day 8. On the contrary, the fraction of (Leu11C+19)+ NK cells increased from 13.5+/-3.1percent (before diving) to 24.0+/-2.7percent (Day 8). The fraction of Leu7+ NK cells and (/( T cells also showed a tendency to rise until Day 8 and to decrease thereafter, but there was no significant difference compared with the values of prediving. CONCLUSION: These results suggest that deep saturation diving has suppressive effect on the cellular immune system especially in CD4+ T lymphocyte subset. But a reciprocal increase in the fraction of NK and (/( T cells may compensate the immunosuppressive effect of deep saturation diving.