Adaptation related to cytokines in man: effects of regular swimming in ice-cold water

The cytokine response after thermal stress (sauna + swimming in ice-cold wa ter) was investigated in subjectively healthy persons. Two groups were stud ied at the end of the winter season: habitual and inexperi- enced winter sw immers. Blood was collected at rest, after a sauna bath and after a short s wim in ice-cold water. Conventional methods and ELISA kits were used to det ermined the blood picture, serum cortisol and dehydroepiandrosterone sulpha te, plasma anti-diuretic hormone (ADH) levels, and the levels of several cy tokines in plasma and in the supernatants of blood cell cultures which were stimulated with lipopolysaccharide (LPS). In regular winter swimmers, the concentrations of plasma interleukin 6 (IL-6), leukocytes, and monocytes at rest were significantly higher than in inexperienced subjects. In experien ced female winter swimmers, the plasma concentration of the soluble recepto r for IL-6 was significantly lower than in inexperienced female swimmers. I n both groups, granulocytosis, haemoconcentration and significant increases in the concentrations of ADH, cortisol and IL-6 were observed after the st imuli. However, the changes in the cortisol concentration were dramatically larger in habitual winter swimmers. A significant correlation was found be tween the delta values of cortisol and the basal concentrations of IL-6. In cell cultures, the LPS-induced release of IL-1 beta and IL-6 was higher at rest in the inexperienced winter swimmers. This release was dramatically s uppressed after exposure to the stimuli in the inexperienced winter swimmer s but tended to increase in the regular winter swimmers. These stresses app ear to challenge both the neuro-endocrine and the immune systems and the re sults indicate that adaptive mechanisms occur in habitual winter swimmers.