Immune dysfunction as a factor in heat illness.

The influence of stress on immune function is well recognized. Indeed for some authors, the changes induced by combinations of vigorous exercise and heat exposure are merely examples of a more generalized stress response. However, there has been surprisingly little consideration of how far disturbances of immune function contribute to heat illness and heat fatalities. The physiology of exercise in hot environments has recently been reviewed. This article provides a brief outline of the main features of heat illness. It then summarizes current knowledge of general immune responses to stress and specific reactions to heat exposure and heavy exercise, and discusses the potential impact of such changes on the outcome of heat illness.