Requirement of the IL-2 Receptor β Chain for the Development of Vγ3 Dendritic Epidermal T Cells

Abstract

Vγ3 TCR cells develop in the fetal thymus and migrate to the skin as dendritic epidermal T cells (DETC). Fetal Vγ3 thymocytes differentiate from immature heat stable antigen (HSA)(high) cells to mature HSA(low) cells and the latter subset predominantly expresses IL-2 receptor β chain (IL-2Rβ). In this study, the role of IL-2Rβ in the development of Vγ3 cells was determined in IL-2Rβ-deficient mice. There was a moderate reduction of mature HSA(low) Vγ3 thymocytes in IL-2Rβ-deficient mice. Small numbers of Vγ3 DETC were detected in the fetal skin of IL-2Rβ-deficient mice, but they were absent in newborn and adult mice. These results suggest that IL-2Rβ may transduce the crucial signal for survival and/or expansion of Vγ3 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 Vγ3 DETC. The dependence of fetal Vγ3 DETC on the expression of IL-2Rβ and the presence of IL-15 mRNA in the fetal epidermis imply an essential role of IL-15 signaling through IL-2Rβ in the selective localization of this γδ T cell subpopulation in the skin.