DYSREGULATED EXPRESSION OF THE IL-2 RECEPTOR BETA-CHAIN ABROGATES DEVELOPMENT OF NK CELLS AND THY-1(-CELLS IN TRANSGENIC MICE() DENDRITIC EPIDERMAL)

The IL-2 receptor beta-chain (IL-2R beta), a specificity-determining s ubunit in the IL-2R complex with a restricted tissue distribution patt ern, is essential for signal transduction. Our previous studies demons trate that the continuous treatment of mice with anti-IL-2R beta resul ted in the complete disappearance of NK cells and Thy-1(+) dendritic e pidermal cells (Thy-1(+) dEC), suggesting that signals through IL-2R b eta are critically involved in development of these lymphocyte subsets , However, these lymphocyte subsets are reported to be apparently unaf fected in the IL-2-deficient mice. To further examine the biological r oles of the IL-2R beta, transgenic mice carrying the IL-2R beta transg ene were generated, In these mice, high levels of the cell surface exp ression of the IL-2R beta were observed in essentially all hematopoiet ic lineage cells, and CD4(+) T cells as well as CD8(+) T cells showed vigorous cell proliferation upon IL-2 stimulation, Surprisingly, NK ce lls marked with a high expression of NK1.1 in the spleen and Thy-1(+) dEC in the skin were completely absent in transgenic mice, However, th e development of other lymphocyte subsets including conventional alpha beta TCR(+) cells, gamma delta TCR(+) cells and B cells remained appa rently intact, From these observations together with previous data on IL-2-deficient mice, we speculate that factors, other than IL-2 that u tilizes the IL-2R beta as its functional receptor subunit, may have a vital role in the development of NK cells and Thy-1(+) dEC, Implicatio ns for possible in vivo functions of over-expressed IL-2R beta are dis cussed.