Thermal stresses reduce natural killer cell cytotoxicity.
Won, Shen-Jeu, and Mao -Tsun Lin.
Department of Microbiology and Physiology, College of Medicine,
National Cheng Kung University, Tainan, Taiwan, R.O.C.
APStracts 2:0169A, 1995.
The effects of different ambient temperatures (Ta) on the splenic NK
cell activity, effector-target cell conjugation activity and NK cell
numbers were assessed in male inbred C3H/HeNCrj mice (7- to 10-week
-old). The splenic NK cytotoxic activities were examined in a 4 h 51Cr
release assay in mouse spleen cells that were obtained 1, 2, 4, 8 or
16 days after exposure to Ta of 22oC, 4oC or 35oC. The percentage of
conjugating lymphocytes was calculated by counting the number of
single lymphocyte bound to single target cell per 400 effector cells.
The numbers of NK cell were expressed by the percentage of 5E6
positive cells. The 5E6 identifies only a subset of NK cells. It was
found that either the splenic NK cell activity, the effector-target
cell conjugation activity or NK cell number began to fall 1 day after
cold (Ta=4oC ) or heat (Ta=35oC) stress. Following a 16-day period of
either cold or heat exposure, the fall in either the splenic NK cell
activity, the effector-target cell conjugation activity or the number
of the 5E6 positive subset of NK cells was still evident. As compared
to those of the control group (Ta=22oC), the cold-stressed mice had
higher adrenal cortisol concentration and lower colonic temperature,
whereas the heat-stressed animals had higher adrenal cortisol
concentration and higher colonic temperature during a 16-day period
of thermal exposure. However, neither cold nor heat stress affected
both the body weight gain and the spleen weight in our mice. Thus, it
appears that thermal stresses produce marked accumulation of adrenal
cortisol and result in suppression of NK activity. The suppression of
splenic NK cell activity after thermal stress may be related to
number of NK cells or effector-target cell conjugation activity, but
not related to body temperature levels.
Received 23 May 1994; accepted in final form 18 April 1995.
APS Manuscript Number A508-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 2 May 1995.