Hyperthermia and human leukocyte functions: effects on response of lymphocytes to mitogen and antigen and bactericidal capacity of monocytes and neutrophils.

It has recently been demonstrated that fever, or hyperthermia, results in enhanced survival of lizards infected by Aeromonas hydrophila. In the present study, the effects of hyperthermia on certain immune functions were assayed in vitro with purified human leukocytes. Lymphocyte transformation responses to the mitogen phytohemagglutinin and the common antigen streptokinase-streptodornase were enhanced at 38.5 degrees C relative to 37 degrees C whether analyzed according to absolute counts per minute of incorporated tritiated thymidine or according to stimulation indexes. Enhancement of response was not accompanied by acceleration of response. Augmentation of transformation response was generally not seen at 40 degrees C; incubation at that temperature was associated with decreased cellular viability. Significant, though small, increases of the bactericidal capacity of polymorphonuclear leukocytes at 40 degrees C relative to 37 degrees C were shown at 1 h with Escherichia coli, Salmonella typhimurium, and Listeria monocytogenes, but not with Staphylococcus aureus. Mononuclear phagocytes did not show enhanced bactericidal capacity at the elevated temperature with any of these organisms in this in vitro system. Hyperthermia may enhance certain host defense mechanisms and warrants further study.