Cellular immunity in highly trained elite racing cyclists during periods of training with high and low intensity

Cellular immunity was measured under resting conditions in 29 highly trained male racing cyclists during a period of low training intensity (winter), and in 15 untrained people. Fifteen of the cyclists were reexamined during a period of high training intensity (summer) together with 10 of the untrained people. Data on lymphocyte subpopulations, natural killer cell activity and lymphocyte proliferative responses were obtained. Changes in any of these immune parameters from low to high training seasons did not differ significantly between the trained and untrained people. The natural killer cell activity was significantly higher in the cyclists, both during the period of low training intensity (39.2±11.6%vs 30.9±6.4%) and during the period of high training intensity (55.2±18.4% vs 33.6±20.3%). Leucocyte, lymphocyte and neutrophil concentrations did not differ between the two groups. The blood mononuclear cell (BMNC) subsets, including CD3+, CD4+, CD8+ and CD16+ cells, and the BMNC proliferative responses following stimulation with either interleukin 2, purified derivative of tuberculin or phytohaemagghitinin did not differ significantly between the groups.