CD16 CROSS-LINKING BLOCKS REARRANGEMENT OF THE TCR-BETA LOCUS AND DEVELOPMENT OF ALPHA-BETA T-CELLS AND INDUCES DEVELOPMENT OF NK CELLS FROM THYMIC PROGENITORS

Mouse thymocytes normally develop into T lymphocytes, but the embryoni c thymus also contains precursor cells capable of developing into NK c ells. Here, we describe conditions that induce pro-T cells to develop into NK cells, CD16 is expressed on thymic pro-T cells. We observed th at CD16 cross-linking during culture of embryonic thymic organs suppre ssed rearrangement of the TCR beta locus (but did not inhibit TCR gamm a locus rearrangement). Rearrangement of the TCR beta locus is normall y required for development to the CD4(+)CD8(+), and this development w as also suppressed by CD16 cross-linking. The ability of CD16 crosslin king to block alpha beta T cell development was not attributable to to xic effects, but rather was accompanied by promotion of development in to NK cells, identified based on molecular and functional criteria. Th ese results suggest that common lymphoid precursors can respond to env ironmental signals to commit to the alpha beta T vs NK developmental p athways.