Heatstroke induces a reduction of natural killer cell activity in rats

Experiments were carried out to determine the changes of natural killer (NK) cell activity that occurred during heatstroke in rats pretreated with or without interleukin-1 (IL-1) receptor antagonist (IL-1ra). After the onset of heatstroke, all the splenic NK cell activity, the effector-target cell conjugation, and the NK cell numbers were decreased in rats. Additionally, an increase in the plasma IL-1 level was associated with arterial hypotension, cerebral ischemia and hyperthermia during rat heatstroke. Pretreatment with an IL-1ra reversed in part the heatstroke-induced inhibition of NK cell activity. Thus it appears that the inhibition of NK cell activity produced by activation of IL-1 receptor mechanism is associated with the increased susceptibility to infection that is well described in heatstroke.