Increased immune activation during and after physical exercise.

The present study has been performed to examine the pattern of immune response during and following a long-duration of physical exercise. We have measured plasma concentrations of serum soluble immune activation markers namely soluble interleukin-2 receptor (sIL-2R), soluble CD8 (sCD8), soluble intercellular adhesion molecule 1 (sICAM-1), soluble CD23 (sCD23), soluble tumor necrosis factor receptor (sTNF-R) and neopterin in 18 individuals before, during (ascent: 3 h, descent: 2 h) and after an alpine tour. Compared to baseline levels, all the parameters were significantly increased on top of the mountain and/or after descent. Within 36 hours after the tour sIL-2R, sCD8 and sICAM-1 decreased. In contrast, sTNF-R and neopterin levels remained higher than baseline throughout the study, only partially decreasing 24 and 36 hours from start. These data show immune system activation induced by physical exercise. The increase of parameters sTNF-R and neopterin, reflecting activation of macrophages, was sustained. The data suggest that immune activation phenomena may be involved in the pathogenesis of impaired immune function after exercise and the exercise-induced asthma.