BCL-2 RESCUES T-LYMPHOPOIESIS IN INTERLEUKIN-7 RECEPTOR-DEFICIENT MICE

Mice lacking functional IL-7 or lL-7R alpha genes are severely deficie nt in developing thymocytes, T cells, and B cells. IL-7 and IL-7 recep tor functions are believed to result in lymphoid cell proliferation an d cell maturation, implying signal transduction pathways directly invo lved in mitogenesis and elaboration of developmentally specific new ge ne programs. Here, we show that enforced expression of the bcl-2 gene in T-lymphoid cells (by crossing in the E mu-bcl-2 transgene) in IL-7R alpha-deficient mice results in a significant restoration of thymic p ositive selection and T cell numbers and function. We propose cell sur vival signals to be the principal function of IL-7R engagement in thym ic and T cell development.