Effect of elevated temperature on cytotoxic effector cells.

Several studies have shown a direct correlation between temperature and immune response. The effect of elevated temperature on cytotoxic effector functions is not well known. In the present study we have investigated the effect of elevated temperatures (38.5 and 40 degrees C) on cytotoxicity of lymphokine-activated killer cells (LAK), monocyte cytotoxicity, cytotoxic T lymphocytes (CTL) and tumor necrosis factor (TNF)-mediated cytotoxicity, and compared them with results at 37 degrees C. LAK cell cytotoxicity was inhibited significantly at 40 degrees C (p < 0.01) and there was no marked difference at 38.5 degrees C (p = 0.17) as compared to 37 degrees C when natural killer (NK)-sensitive K562 cells were used as target. When NK-resistant Raji cells were used as a target, cytotoxicity was inhibited at 40 degrees C (p = 0.33). Monocyte cytotoxicity was enhanced at 40 degrees C (p = 0.19) as well as at 38.5 degrees C (p = 0.38) as compared to 37 degrees C but differences were not statistically significant. Lipopolysaccharide (LPS) enhanced monocyte cytotoxicity. LPS-stimulated enhancement was further enhanced significantly at 40 degrees C (P < 0.05) and 38.5 degrees C (p < 0.05). Cytotoxicity of CTL was significantly inhibited at 38.5 compared to 37 degrees C (p < 0.0002). TNF-mediated cytotoxicity was significantly enhanced at 40 degrees C (p < 0.0004) and 38.5 degrees C (p < 0.001).