Responsiveness of human natural killer cells during acute, incremental exercise up to exhaustion (original) (raw)

Eight healthy male subjects performed a cycle ergometer incremental exercise up to exhaustion to study possible relationships between excess CO 2 production (CO 2-exc ) and natural killer (NK) cells, measured in terms of concentration (NK abs ) and as a percentage of lymphocytes in peripheral blood (NK%). A parabola-like regression equation with its vertex downwards best fit the relationship between CO 2-exc at W max and the difference between NK cell measurements at the maximum workload (W max ) and at the workload corresponding to the anaerobic threshold (W AT ). For NK cell concentration, the best equation was NK abs (cells/mm 3 )=248.8413-0.3105 CO 2-exc (ml min -1 )+0.0001 CO 2-exc 2 (ml min -1 ) (p=0.044). For NK cells expressed as a percentage, the best equation was NK(%)=108.7636-0.1414 CO 2-exc (ml min -1 )+0.00001 CO 2-exc 2 (ml min -1 ) (p=0.032). Thus, the higher was the CO 2-exc the lower was the increase in both NK cell measurements at W max with respect to the value observed at W AT . However, when CO 2-exc reached more elevated values, then the direction of this relationship was inverted. It may be concluded that when strenuous exercise is performed, an anti-inflammatory/performance-preserving event takes place, while recovery towards a pro-inflammatory/anti-infection state tends gradually to re-establish when a subject's anaerobic power becomes too high.