OBJECTIVETo investigate the changes in white blood cell populations, lymphocyte subsets and stress-related cytokines after long-term exercise training and address the association between blood cell changes and stress-related cytokines in relation to exercise.

METHODSA total of 1038 professional athletes were examined for CBC with Sysmex XE2100, and the T, B, and NK lymphocyte subsets were analyzed with flow cytometry. The testees' RNA were extracted from 1 ml whole blood, and the stress-related cytokines such as CRP, SELL,TNF-α, IL8, IL4, ICAM1, PECAM1, IL6, and NOS were tested by multi-RT-PCR and fragments separated by capillary electrophoresis using Beckman Coulter GeXP system.

RESULTSNo obvious difference was found in WBC count between the athletes, all within normal range. The proportion of lymphocytes was increased in the athletes by 20%-40% in comparison with the normal level, and the CD3+, CD3+CD4+, and CD3+CD8+ T, B, and NK lymphocyte subsets were all lower in the athletes than the normal range. The cytokine expressions exhibited no significant gender-related difference. IL-8, TNF-α and SELL expressions increased while IL-4 decreased in the athletes. Correlations were noted between the changes of the cells and the cytokine expressions.

CONCLUSIONLong-term exercise training affects the immune system and cause stress, which may potentially increase the risks of some chronic diseases.