Effects of acute physical stress on immune competence in pigs

Some interrelations between physical stress and immune competence were studied in pigs. One group of pigs underwent 2 intense short-term treadmill exercise tests, separated by an interval of 1 week, and another group served as controls. In vitro production of interferon alpha by blood mononuclear cells and the ability of lymphocytes to proliferate and produce interleukin 2 were chosen as markers of immune competence; plasma concentrations of cortisol, lactate, and purines were used as markers of physical stress. Blood samples were drawn from a catheter in situ 60 minutes before, immediately after, and at 10, 30, and 60 minutes, and 7, 24, and 72 hours after exercise. Physical stress resulted in immediate increase in the plasma concentrations of cortisol, lactate, and hypoxanthine, but had no effect on the blastogenic capability of lymphocytes or on their interleukin-2 production on either of the test occasions. Ability of blood mononuclear cells to produce interferon alpha in vitro was not affected by exercise stress.