Effects of voluntary exercise on immune function in rats.

We investigated effects of voluntary wheel running on specific antibody responses to Keyhole Limpet Hemocyanin (KLH) and on mitogen-stimulated lymphocyte proliferation in adult male rats. Each subject was placed in a running wheel for 12 h daily during the dark portion of the light cycle for a total of 8 weeks. For experimental animals the wheels rotated freely, enabling subjects to exercise at will, while for control animals the wheels were prevented from rotating. Subjects were immunized with KLH (25 micrograms) 5 weeks into the study, and blood samples were collected intermittently from the tail for 3 weeks and later assayed for anti-KLH antibody levels. At the end of the study, subjects were sacrificed and spleens were dissected and assayed for lymphocyte proliferative responses to the mitogen Concanavalin A. Exercised rats gained less weight and had higher splenic proliferative responses than control rats; however, there were no significant group differences in anti-KLH antibody levels.