Differential requirement for humoral factors for IL-2R expression of murine T cell subsets, Th1, Th2, and CD8Th clones.

Three types of alloreactive T helper (Th) cell clones, Th1, Th2, and CD8Th, were examined for the requirement of costimulatory factors for IL-2 receptor (IL-2R) expression and proliferation. When stimulated with allogeneic spleen adherent cells, these Th cell clones all expressed IL-2R strongly, whereas they expressed the receptor only weakly when subjected to allogeneic B cell stimulation. The addition of partially purified IL-2RIF to Th1, Th2, or CD8Th cell clones stimulated with B cell antigen-presenting cells increased the IL-2R expression of Th1 and CD8Th cell clones but not of the Th2 cell clone. Conversely, IL-1 up-regulated IL-2R expression of Th2 cell clones stimulated with B cell APC but not of Th1 and CD8Th cell clones. Neither IL-2RIF nor IL-1 induced IL-2R expression of unstimulated Th cell clones. IL-2R expressed in the presence of these costimulators contributed to IL-2-dependent proliferation of these cells. Thus, the expression of IL-2R was indicated to be regulated differently in three types of Th cell subsets through different cytokines.