MECHANISM OF EXERCISE-INDUCED AUGMENTATION OF LYMPHOKINE-ACTIVATED KILLER (LAK) CELL-ACTIVITY IN THE HORSE

Intense exercise affects various parameters of the immune system. The overall effect of exercise on immune function is dependent upon the ph ysical condition of the subject, the intensity and duration of the exe rcise period, and the immune parameter assessed. Unconditioned horses subjected to a single bout of intensive exercise exhibit multiple alte rations in immune function, including an augmentation of lymphokine ac tivated killer (LAK) cell function. This increase in LAK cell activity is not due to an increase in circulating LAK precursors. While periph eral blood mononuclear cells from exercising horses exhibit greater re sponsiveness to IL-2, this is not due to an increase in IL-2 receptor expression. LAK cell generation in vitro is augmented by those catecho lamines and neuropeptides which are produced during exercise, suggesti ng a direct effect of these compounds on LAK cell generation at a step post IL-2 receptor binding.