Effects of thermal shocks on interleukin-1 levels and heat shock protein 72 (HSP72) expression in normal human keratinocytes.

Interleukin-1 expression is reported to be modified under a number of cell conditions including physiological stress, injury and activation. We report the effects of the physiological stresses cold and heat shock on IL-1 levels in keratinocytes. Having observed that normal human skin obtained from plastic surgery, usually stored at 4 degrees C for a few hours, highly expressed HSP72, a constant feature of stressed human keratinocytes, we wondered whether this induction could be linked to a cold shock and to modification of IL-1 levels in keratinocytes. Cultured keratinocytes were incubated at 4, 37, 40 and 43 degrees C for 1.5, 4, 8 and 16 h in a defined medium. HSP72 expression was studied by immunohistochemistry and immunoblot and IL-1 was quantified using specific and sensitive radioimmunoassay. Our findings showed that intracellular IL-1 alpha and IL-1 beta levels are not significantly modified by thermal shock. HSP72 is only induced after cell exposure to 43 degrees C and is not a cold-shock protein. These results demonstrate that thermal stress is not an inductive signal for IL-1 modification in keratinocytes.