Requirement of the IL-2 receptor β chain for the development of Vγ3 dendritic epidermal T cells

V gamma beta TCR cells develop in the fetal thymus and migrate to the skin as dendritic epidermal T cells (DETC). Fetal V gamma beta thymocytes differentiate from immature heat stable antigen (HSA)(high) cells to mature HSA(low) cells and the latter subset predominantly expresses IL-2 receptor beta chain (IL-2R beta). In this study, the role of IL-2R beta in the development of V gamma beta cells was determined in IL-2R beta-deficient mice. There was a moderate reduction of mature HSA(low) V gamma beta thymocytes in IL-2R beta-deficient mice. Small numbers of V gamma beta DETC were detected in the fetal skin of IL-2R beta-deficient mice, but they were absent in newborn and adult mice. These results suggest that IL-2R beta may transduce the crucial signal for survival and/or expansion of V gamma beta cells in the fetal thymus and in the fetal skin. In normal mice, IL-15 but not IL-2 mRNA was expressed in the fetal epidermis and exogenous addition of low concentration of IL-15 to fetal skin organ culture induced proliferation of V gamma beta DETC. The dependence of fetal V gamma beta DETC on the expression of IL-2R beta and the presence of IL-15 mRNA in the fetal epidermis imply an essential role of IL-15 signaling through IL-2R beta in the selective localization of this gamma delta T cell subpopulation in the skin.