Temperature-mediated processes in immunity: differential effects of low temperature on mouse T helper cell responses.

A low culture temperature of 27 degrees C inhibited mouse primary in vitro anti-hapten plaque-forming cell responses to a thymus-dependent (TD) antigen (Ag) (trinitrophenyl-keyhole limpet hemocyanin, TNP-KLH). In contrast, the magnitudes of secondary responses to TNP-KLH or primary responses to a thymus-independent (TI) Ag (TNP-lipopolysaccharide (LPS)) were unaffected. The low-temperature-sensitive step in the primary TD response occurred relatively early and preceded interleukin 2 (IL-2) secretion. Furthermore, the low-temperature-induced suppression could be obviated (rescued) by recombinant IL-2 or IL-4, but not by IL-1. Thus, the low temperature appeared to inhibit the function of virgin Th cells by preferentially affecting T cell-derived interleukin synthesis/secretion and not other cellular activities. These results also imply fundamental differences between the activation requirements of memory and virgin Th cells.