Effect of Acute Physical Exercise on Lymphocyte Subpopulations in Trained and Untrained Subjects

: To clarify the difference in immunity between untrained subjects and well-trained athletes, the number of total leukocytes (WBC), lymphocytes, and neutrophils, percentages of various lymphocyte subpopulations (OKT3, OKT4, OKT8, Leu7, OKla1), and the levels of lymphocyte transformation response to phytohemagglutinin (PHA) were determined in five untrained male subjects and six male athletes before, immediately after, and 24 and 72 h after acute physical exercise at 60% of VO2max for 2 h. Exercise produced a significant rise in the number of WBC, lymphocytes, and neutrophils in both groups. Immediately after exercise, the percentage of OKT3 or OKT4 positive cells had significantly decreased in both groups, whereas that of OKT8 positive cells had markedly increased only in the athletes. Neither group showed any change in the percentage of OKla1 positive cells. In both groups, the response of lymphocytes to PHA immediately after exercise was significantly lower than before, 24 h and 72 h after exercise. The level of Leu7 positive cells rose remarkably immediately after exercise in the athletes, but not significantly in the untrained subjects. These results suggest that an increase in Leu7 positive cells provides added host defense capacity in trained athletes during periods of stress which impair T-lymphocyte function.