Immune parameters of untrained or exercise-trained rats after exhaustive exercise.

The effect of a single exhaustive swimming exercise bout on immune competence of untrained or exercise-trained female Wistar rats was compared with the competence of control sedentary rats. After the exhaustive exercise bout, the blastogenic response to concanavalin A by spleen cells of untrained rats was extensively suppressed, whereas the response of the trained rats was only marginally suppressed. The suppressed immune competence of the untrained rats after the exhaustive exercise was associated with an increase in immune-suppressive activity of splenic lymphocytes. The macrophages of the untrained rats and of the control sedentary rats were slightly immune suppressive to normal spleen cells through a prostaglandin-dependent mechanism. The addition of prostaglandin E2 (PGE2) to the blastogenesis cultures revealed that the spleen cells of untrained rats were unusually sensitive to the suppressive effects of PGE2. In contrast to the untrained rats, the marginal level of immune suppression in trained rats after the exhaustive exercise was associated with a lesser degree of lymphocyte-suppressive activity, an immune stimulatory activity by the splenic macrophages, and an insensitivity of the splenic lymphocytes to the suppressive effects of PGE2.