Abstract Fever has been shown by others to have a beneficial effect on the survival of animals challenged with bacteria. The febrile animals exhibited increased leukocyte accumulation at the site of bacterial inoculation. In order to investigate further these observations, as well as their possible relevance to human temperature elevation, human leukocytes were assayed in vitro for production of and response to leukocyte migration inhibition factor (LIF) at normal (37°C) and hyperthermic (38.5°C) temperatures. Leukocyte migration was assayed at both 37° and 38.5°C, by using an agarose plate technique, with exposure of the cells to supernatant fluids derived from stimulated and unstimulated leukocytes incubated at 37 or 38.5°C. Hyperthermia (38.5°C) was consistently associated with greater spontaneous and stimulated LIF production by human mononuclear leukocytes. Hyperthermia was associated with decreased spontaneous leukocyte migration and greater inhibition of leukocyte migration by LIF-rich supernatant fluids. Migration at 38.5°C after exposure to LIF produced at 38.5°C was greatly reduced relative to migration at 37°C in response to LIF produced at 37°C (p 0.005). Results were similar with mitogen- and antigen-stimulated LIF. The results suggest one possible mechanism by which hyperthermia may benefit the
Roberts et al. (Tue,) studied this question.