Effect of heat shock on susceptibility of normal lymphoblasts and of a heat shock protein 70-defective tumour cell line to cytotoxic T lymphocytes in vitro.

The effect of heat shock pretreatment of target cells on their lysability by cytotoxic T lymphocytes was analysed. Killing of Concanavalin A-stimulated normal lymphocytes by minor or major histocompatibility antigen-specific cytotoxic T lymphocytes is unchanged or even slightly enhanced after heat shock, whereas cells of the myeloma line Y3, which is derived from one of the lymphocyte donor strains, become nearly resistant to killing after the same pretreatment. Cold target inhibition experiments show that heat-shocked cells are recognized specifically and that untreated and heat-shocked target cells possess similar inhibitory potential. Y3 cells are unable to express the strongly heat-inducible heat shock protein of 70 kDa (hsp70) after heat shock; the acquired resistance is thus independent of hsp70 induction. Possible mechanisms of the different lysability seen in lymphoblasts and tumour cells after heat shock are discussed.