Changes in peripheral blood lymphocyte subsets associated with marathon running

The percentage of peripheral blood mononuclear leukocytes that reacted with monoclonal antibodies specific for T-lymphocytes (CD3 cells), the helper/inducer subsets (CD4 cells), and cytotoxic/suppressor subsets (CD8 cells) of T-lymphocytes, and cells with NK activity (CD16 cells) were enumerated by fluorescence-activated flow cytometry for samples obtained immediately before and after the marathon running. It was found that long-term physical exercise resulted in a significant (P < 0.04 for relative and P < 0.008 for absolute lymphocytes) reduction in CD3 cells. A significant (P < 0.009) percentage change was also observed in B lymphocytes (CD19 cells) right after the marathon. The number of NK (CD16 cells) lymphocyte subsets was significantly (P < 0.05 for relative and P < 0.03 for absolute lymphocytes) changed. No significant changes were recorded for CD4, CD8, or CD4/CD8 ratios after the marathon run. A marked leukocytosis was noticed after the endurance exercise and the mean white blood cell (WBC number was increased from 7.8 +/- 2.6 to 22.9 +/- 2.8 x 10(9) cells x 1-1) count was changed by a factor of 2.9. The mean serum cortisol was significantly (P < 0.0001) increased. No hematocrit change was recorded in subjects pre- to post-run. The results of this study demonstrated that long-term physical exercise (marathon running) influenced the T-cell subsets remarkably and produced leukocytosis that was stress dependent and correlated with the increased serum cortisol levels and not the hemoconcentration.