Prolonged exercise suppresses antigen-specific cytokine response to upper respiratory infection

Fatiguing exercise has been associated with an increased susceptibility to infection. This study examined the antigen-specific T-helper (Th) type 1 an d Th type 2 cytokine response to herpes simplex virus (HSV) infection after an acute bout of fatiguing exercise. Male BALB/cJ mice ran on a treadmill (Ex) until voluntary fatigue (similar to2.5 h), and control mice were handl ed and remained next to the treadmill. Mice were infected with HSV 20 min a fter exercise. Mice were killed 2 or 7 days postinfection, and sera and spl eens were taken for the determination of HSV-specific serum IgM, splenocyte cytokine production during culture with HSV, and splenocyte natural killer cell cytotoxicity. Both Th type I [interleukin (IL)-2, interferon-gamma, I L-12] and Th type 2 (IL-10) cytokine production in spleen cell cultures, as well as natural killer cell cytotoxicity, decreased in Ex on day 2 postinf ection. On day 7 postinfection, there was no difference in HSV-specific ser um IgM or cytokine production by cells from control and Ex mice, with the e xception of decreased IL-12 in Ex mice. These findings suggest that fatigui ng exercise may alter the kinetics of antigen-specific cytokine production.