Lymphocyte function and cytokine production during incremental exercise in active and sedentary males and females

This study examined the effects of acute continuous incremental exercise on lymphocyte mitogenic function and cytokine production in physically active and sedentary males and females. Physically active (n = 32) and sedentary (N = 32) male and female subjects were randomly assigned to an exercise or control condition. Exercise involved a continuous incremental protocol consisting of cycling for 3 periods of 6 min at workrates corresponding to 55%, 70% and 85% VO2peak. Blood samples were drawn from a venous catheter at baseline, 6 min, 12 min and 18 min, and 2 h following completion of exercise. Relative to baseline and control condition the percentage of T (CD3+) and B cells (CD19+) significantly decreased, and the percentage of NK cells (CD3-CD16+CD56+) increased (p < 0.001) during each stage of the incremental exercise test. The proliferative response to ConA was suppressed, enhanced, or unchanged using 1.25 micrograms/ml, 2.5 micrograms/ml and 5.0 micrograms/ml ConA, respectively. The in-vitro production of IL-1 and IFN-gamma increased during each workload. In contrast IL-4 production did not change during exercise. The resting and exercise induced alterations in lymphocyte function and cytokine production were independent of gender and fitness level, and returned to baseline 2 h into recovery. The in-vitro production of IFN-gamma and IL-4 suggests that physical activity may alter the balance of TH1 and TH2 lymphocytes.