The influence of exercise training status on antigen-stimulated IL-10 production in whole blood culture and numbers of circulating regulatory T cells.

Highly trained athletes are associated with high resting antigen-stimulated whole blood culture interleukin (IL)-10 production. The purpose of the present study was to examine the effects of training status on resting circulating T regulatory (Treg) cell counts and antigen-stimulated IL-10 production and the effect of acute bout of exercise on the Treg response. Forty participants volunteered to participate and were assigned to one of the four groups: sedentary (SED), recreationally active (REC), sprint-trained athletes and endurance-trained athletes (END). From the resting blood sample, CD4(+)CD25(+)CD127(low/-) Treg cells and in vitro antigen-stimulated IL-10 production were assessed. Ten REC subjects performed 60 min cycling at 70 % of maximal oxygen uptake and blood samples for Treg analysis were collected post- and 1 h post-exercise. IL-10 production was greater in END compared with the other groups (P < 0.05). END had a higher Treg percentage of total lymphocyte count compared with SED (P < 0.05). A smaller proportion of Treg CD4(+) cells were observed in SED compared with all other groups (P < 0.05). IL-10 production significantly correlated with the proportion of Tregs within the total lymphocyte population (r s = 0.51, P = 0.001). No effect of acute exercise was evident for Treg cell counts in the REC subjects (P > 0.05). Our results demonstrate that high training loads in END are associated with greater resting IL-10 production and Treg cell count and suggest a possible mechanism for depression of immunity commonly reported in athletes engaged in high training loads.