The effect of whole body heat exposure and of cooling the hypothalamus on antibody titre in the rat.

In rats implanted with chronic hypothalamic thermodes and immunized with sheep erythrocytes, body temperature was increased, 4 h per day for 2 weeks, either by exposing the animals to external heat or by cooling the preoptic area. The titre of antibodies against sheep erythrocytes was nearly tripled by preoptic cooling but was drastically decreased by heat exposure. These opposing effects of active and passive increases in body temperature indicate that factors other than the change in body temperature must also have played a significant role in modifying the humoral immune response.