The effect of hypothalamic temperature on the immune response in the rat.

To clarify the role of febrile temperatures on the immune system, rats were immunized with sheep erythrocytes and their core temperature was then changed by continuously cooling or heating the preoptic area for five days. Core temperatures of up to 2 degrees C above or below normal were associated with a high titre of antibodies against sheep erythrocytes, whereas larger displacements of core temperature, as well as normal temperature, were associated with a low titre. These results are at variance with the idea that the production of antibodies is proportional to body temperature. It is suggested that the immunostimulation elicited by heating and cooling the preoptic area, and by inference that the immunostimulation associated with fever, could be due to factors other than the change in body temperature.