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-l (IL-I) receptor antagonist (IL-1ra). After the onset of heatstroke, all the splenic NK cell activity, the effector-target cell c onjugation, and the NK cell numbers were decreased in rats. Additionally, a n increase in the plasma IL-l level was associated with arterial hypotensio n, cerebral ischemia and hyperthermia during rat heatstroke. Pretreatment w ith 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-I receptor mechanism is associated with the increased susceptibility to infection that is well described in heatstroke. (C) 2000 Elsevier Science Ltd. All rights reserved.