The effect of the supernatant of the thymic epithelial cell line, IT-45R1 (STEL), on thymocyte reactivity to mitogens.

The supernatant of the thymic epithelial cell line, IT-45R1 (STEL), previously proven to induce the differentiation of T-lymphocyte progenitors in the rat bone marrow, was examined for its influence on the differentiation of rat thymocytes. Preincubation with STEL increased the reactivity of rat thymocytes to Con A and PHA. The effect of STEL was found to be significant within a wide range of STEL dilution even at 1:1000, but not at 1:10000, showing dose-dependency of this effect. It took about 24 h for STEL to increase the responses of thymocytes to Con A and PHA. From these results, it is concluded that STEL could also induce the differentiation of rat thymocytes.