Exercise suppresses macrophage antigen presentation

This study determined the effects of exercise on the ability of macrophages (M phi) to present antigen to T cells. Pathogen-free male Balb/c mice (8 /- 2 wk of age) were randomly assigned to either home cage control, moderat e exercise (Mod; 18 m/min, 5% grade, 0.5 h/day), exhaustive exercise (Exh, 18-30 m/min, 3 h/day), or treadmill control groups. The mice underwent trea tments for 4 days during peritoneal thioglycolate inflammation. Peritoneal M phi were harvested, purified, and incubated with chicken ovalbumin (C-OVA ; 0-10 mg/ml) for 18 h. M phi were then cocultured with C-OVA-specific T ce lls for 48 h, and the supernatants were analyzed via ELISA for interleukin- 2 as an indication of M phi antigen presentation (AP). Exh exhibited suppre ssed (similar to 25-34%) M phi AP across a wide range of C-OVA doses when m easured immediately, 3, and 24 h postexercise. In contrast, Mod had reduced M phi AP only at 3 h postexercise. M phi AP was also lower in the treadmil l control (4-27%) compared with the home cage control group, but was signif icantly higher than Exh. The reduction in M phi AP was not due to exercise- induced differences in M phi number, percentage, or expression of intercell ular adhesion molecule-1, B7-2, or major histocompatability complex II, mol ecules important in AP. In conclusion, our data lend evidence that may help explain the increased incidence of infection observed after prolonged exha ustive exercise or overtraining.