AJP - Regulatory, Integrative and Comparative Physiology, Vol 259, Issue 1 1-R6, Copyright © 1990 by American Physiological Society
A feverlike response inhibits expression of delayed-type hypersensitivity in rats
M. Banet
Institute for Normal and Pathological Physiology, Philipps University, Marburg, Federal Republic of Germany.
To determine the effect of fever on cell-mediated immunity, the preoptic
area of male rats was cooled after either a sensitizing or a challenge
injection of keyhole-limpet hemocyanin, and the delayed-type
hypersensitivity inflammatory response was measured. Cooling the preoptic
area for 5 days, starting shortly after the sensitizing injection of
antigen, did not speed up the development of the capacity to respond to a
challenge injection of antigen nor did it influence the magnitude of the
resulting inflammatory response. In sensitized animals, however, cooling
the preoptic area for 24 h, starting shortly after the challenge injection
of antigen, raised core temperature to an average of 40 degrees C and
decreased the magnitude of the inflammatory response by 25%, whereas
heating the preoptic area caused a fall in core temperature to an average
of 35 degrees C and increased the response by about 25%. There was, in
fact, a moderate negative correlation (r = 0.85) between core temperature
and the size of the inflammation. Furthermore, the inhibitory effect of
cooling the preoptic area could be blocked neither by adrenalectomy nor by
diazepam (0.5 mg/kg body wt), a drug that suppresses most endocrine
responses to stress. It is therefore suggested that the expression of
delayed-type hypersensitivity is inhibited at elevated body temperatures
and that fever may thus weaken the defenses of the host against infection.
