hyperthermia increases natural killer cell cytotoxicity against sw-872 liposarcoma cell line

background: although there is convincing data in support of the effectiveness of hyperthermia in tumor therapy, the molecular mechanisms underlying the clinical effects of hyperthermia are still poorly understood. objective: to investigate natural killer (nk) cell cytotoxicity against heat-treated sw-872 and hela tumor cell lines. methods: nkg2d ligands and hla class i transcription were examined using quantitative real-time pcr in treated tumor cell lines at 0, 2, 4, 6 and 12 h following thermal treatment at 39c and 42c for 1 h. the expression of mica/b, ulbp1 and ulbp2 were also determined by flow cytometry. nk92-mi cytotoxic activity against heat-treated target cell lines was assessed by ldh release as well as annexin-v and 7-aad assays. results: our results showed that heat treatment at 39c improved the cytolytic activity of nk cells against sw-872 cells without increasing nkg2d ligand concentration or decreasing hla class i levels. conclusion: the observed increase in the cytotoxicity of nk cells against sw-872 cells after hyperthermia does not coincide with changes in mica/b, ulbp1 and ulbp2 ligands of nkg2, however, the expression of other ligands in target cells may have made the cells susceptible to the cytotoxic effect of nk cells.