Original investigations: Anaerobic exercise causes transient changes in leukocyte subsets and Il-2R expression

There is evidence that the stress of intense athletic competition and training depresses cellular immunity and predisposes athletes to increased infection. This paper reports changes in circulating leukocyte subsets of trained (group I: VO_2max = 67.2 ± 5.4 ml. kg⁻¹min⁻¹; age = 22.0 ± 6.2 yr) and untrained (group II: VO_2max = 55.0 ± 4.9 ml. kg⁻¹min⁻¹; age = 21.4 ± 2.0 yr) males following 1 min of bicycle ergometry at maximum effort. Significant post-exercise increases in concentrations of total leukocytes, monocytes, lymphocytes, CD3+, CD4+, CD8+ lymphocytes were observed in both groups (all P < 0.01). The CD4/CD8 ratio decreased significantly (P < 0.01) but the granulocyte concentration was not altered (P> 0.05). Despite groups I and II not differing in either peak power or total work performed during the exercise test (P > 0.05), group II had a significantly greater concentration and percentage of CD8+ lymphocytes immediately after exercise (P < 0.01). All of the early changes were transient, with normalization occurring within 1 h. Only trained subjects showed a significant decrease in the percentage of CD25+ lymphocytes following PHA stimulation of whole blood obtained 6 h post-exercise. Alterations in leukocyte subpopulations found in response to predominantly anaerobic exercise appear to be associated with a significant, but possibly transient, alteration in the mitogenic responsiveness of lymphocytes that is restricted to aerobically trained subjects.