HEAT-SHOCK ENHANCES THE SUSCEPTIBILITY OF TUMOR-CELLS TO LYSIS BY LYMPHOKINE-ACTIVATED KILLER-CELLS

Objective: To determine whether heat-treated thyroid cancer cells augm ent the susceptibility of target cells to lysis by autologous lymphoki ne-activated killer cells. Design: Peripheral blood lymphocytes from p atients with thyroid cancer were incubated with recombinant interleuki n 2 (100 U/mL) for 7 days, and thyroid cancer cells obtained from surg ical specimens were heated at 44 degrees C for 20 minutes and incubate d at 37 degrees C for 18 hours before performing the radioactive chrom ium Cr 51 release assay. Results: The susceptibility of heat-treated t hyroid cancer cells to lysis by autologous and allogeneic lymphokine-a ctivated killer cells was significantly greater than that of untreated tumor cells. The mechanism of enhanced susceptibility was unclear. Ho wever, the effect depended on de novo protein synthesis, because inhib ition of RNA synthesis by dactinomycin completely abolished the heat-e nhanced susceptibility of tumor cells. Conclusion: Immunotherapy combi ned with hyperthermia may be useful in management of thyroid cancer.