Effects of heat shock on cytolysis mediated by NK cells, LAK cells, activated monocytes and TNFs alpha and beta.

We have recently shown that a heat treatment of a murine target cell line, WEHI 164, induces resistance to lysis mediated by tumour necrosis factors alpha (TNF-alpha) and beta (TNF-beta). In the present study the effect of the heat shock of target cells on cytotoxicity mediated by natural killer cells (NK cells), lymphocyte-activated killer cells (LAK cells), activated monocytes, TNF-alpha, and TNF-beta was investigated. First, WEHI 164 cell line and six human cell lines (ME 180, K 562, U 937, HeLa, MCF7, and SK-OV 3) were screened for their sensitivity to different forms of lysis, and then sensitive cell lines were heat-treated. Pretreatment of target cells at 42 degrees C for 45-60 min also rendered human target cell lines more resistant to lysis by rTNFs, and the acquired resistance was accompanied by an increased resistance to activated monocytes, but not to NK cells or LAK cells. Thus, the heat-induced resistance mechanisms capable of protecting target cells from lysis by rTNFs and by activated monocytes do not elicit resistance to lysis by NK cells and LAK cells, supporting the hypothesis that mediators other than TNFs are involved in NK cell- and LAK cell-mediated killing.