Comparison of anti-leukemic immunity against U937 cells in endurance athletes versus sedentary controls

To examine whether endurance athletes have higher antileukemic immunity tha n sedentary controls or not, we isolated peripheral blood mononuclear cells (MNC) from cyclists and sedentary controls to prepare conditioned media (C M) with various doses of phytohemagglutinin (PHA). The prolife ration-in hi biting and differentiation-inducing activities of these PHA-MNC-CM on huma n leukemic U937 cells were investigated. Our results show that the growth i nhibition activity of cyclists' PHA-MNC-CM were higher than that of control s. The dosage of PHA used to prepare MNC-CM to achieve about 90% growth inh ibition was 5 mug/ml in the control group and was 2 mug/ml in the athletes group. The differentiation-inducing effects were evaluated by morphological scoring, superoxide production, and monocyte-associated antigen expression (CD14 and CD68). These three parameters all demonstrated the differentiati on-inducing effect of MNC-CM increased with increasing dose of PHA. These e ffects were significantly greater in the athletic when compared to the sede ntary control group at all doses of PHA. The levels of TNF-alpha and IFN-ga mma in PHA-MNC-CM increased in a PHA dose-dependent manner and were much hi gher in the athletic group when compared to the controls. We conclude that the capacity of endurance athletes to activate anti-leukemic immunity is si gnificantly higher than that of sedentary controls.