T-CELL RECEPTOR-GAMMA-DELTA AND GAMMA-TRANSGENIC MICE SUGGEST A ROLE OF A GAMMA-GENE SILENCER IN THE GENERATION OF ALPHA-BETA-T-CELLS

A T lymphocyte expresses on its surface one of two types of antigen receptor, T-cell receptor αβ or T-cell receptor γδ, encoded by a pair of somatically rearranged α and β or γ and δ genes. It has been suggested that αβ T cells are generated only from precursor T cells that failed to rearrange γ and δ genes in a functional form. However, we found that transgenic mice constructed with functionally rearranged γ and δ genes produce a normal number of αβ T cells. The transgene γ present in these αβ T cells is repressed apparently through an associated cis DNA element (silencer). We propose that some T-cell precursors are committed to generate αβ T cells independent of the rearrangement status of their γ gene and that this commitment involves activation of a factor(s) that interacts with the γ gene-associated silencer.