Exercise suppresses macrophage antigen presentation

This study determined the effects of exercise on the ability of macrophages (Mφ) 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, moderate 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 treatments for 4 days during peritoneal thioglycolate inflammation. Peritoneal Mφ were harvested, purified, and incubated with chicken ovalbumin (C-OVA; 0-10 mg/ml) for 18 h. Mφ were then cocultured with C-OVA-specific T cells for 48 h, and the supernatants were analyzed via ELISA for interleukin- 2 as an indication of Mφ antigen presentation (AP). Exh exhibited suppressed (~25-34%) Mφ AP across a wide range of C-OVA doses when measured immediately, 3, and 24 h postexercise. In contrast, Mod had reduced Mφ AP only at 3 h postexercise. Mφ AP was also lower in the treadmill control (4- 27%) compared with the home cage control group, but was significantly higher than Exh. The reduction in Mφ AP was not due to exercise-induced differences in Mφ number, percentage, or expression of intercellular adhesion molecule- 1, B7-2, or major histocompatability complex II, molecules important in AP. In conclusion, our data lend evidence that may help explain the increased incidence of infection observed after prolonged exhaustive exercise or overtraining.