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 °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�C. LAK cell cytotoxicity was inhibited significantly at 40�C (p < 0.01) and there was no marked difference at 38.5�C (p = 0.17) as compared to 37 �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�C (p = 0.33). Monocyte cytotoxicity was enhanced at 40�C (p= 0.19) as well as at 38.5�C (p = 0.38) as compared to 37�C but differences were not statistically significant. Lipopolysaccharide (LPS) enhanced monocyte cytotoxicity. LPS-stimulated enhancement was further enhanced significantly at 40�C (p < 0.05) and 38.5�C (p < 0.05). Cytotoxicity of CTL was significantly inhibited at 38.5 compared to 37�C (p < 0.0002). TNF-mediated cytotoxicity was significantly enhanced at 40�C (p < 0.0004) and 38.5�C(p < 0.001).