Lymphokine activated killer cell activity following voluntary physical activity in mice

The effect of eight weeks of voluntary wheel running exercise in female, outbred Swiss Webster mice on baseline splenic natural killer (NK) cell and interleukin-2 stimulated lymphokine activated killer (LAK) cell activity was studied. NK cell cytolytic activity against YAC-1 tumour targets was measured using a 51Cr release assay at the completion of a wheel running episode (end of dark cycle) or at 96 h after cessation of wheel running. LAK cell activity against tumour targets was generated from splenic NK cells by in vitro stimulation for 3 days with recombinant interleukin-2 (rIL-2). Wheel running was not associated with increases in baseline NK cytolytic activity either when sampled as a training effect (96 h after exercise) or immediately after exercise. Following an episode of wheel running exercise, LAK activity was significantly higher in the physically active compared to sedentary animals. These results support the concept that spontaneous wheel running activity enhances lymphokine activated killer cell activity following a cycle of active running; whether this greater LAK activity involves changes in IL-1, IL-2, or other cytokine concentrations or in the expression of IL-2 receptors on NK/LAK cells after exercise warrants further investigation. Given the clinical use of IL-2 to stimulate LAK cells in adoptive immunotherapy, it is possible (although untested) that exercise may have a potentially beneficial role as a treatment modality for some human cancers.