Abrogation of the Allelic Exclusion in a T Cell Receptor β Chain Gene Transgenic Mouse Strain

Abstract

The expression of endogenous T cell receptor (TcR) β chains in a TcR β chain gene transgenic mouse (TGM) strain was examined. Unlike many other TGM strains reported, a considerable proportion of T cells from the thymus and spleen as well as organ cultured fetal thymus from our TGM express endogenous TCR β chains on their surface. Compatible with this was the elucidation of VDJ rearrangement of endogenous β chain genes by PCR. Three color flowcytometric analysis of thymus cell subpopulations revealed that the expression levels of both endogenous and transgenic TcR β genes are regulated in a maturational stage specific manner. Splenic T cells contained a several fold higher percentage of endogenous TcR β positive cells than thymus cells, suggesting a role of TcR on T cell peripherization. Vβ6 positive cells were deleted in the TGM carrying minor lymphocyte stimulating (Mls)-l^a antigen, indicating that the endogenous TcR β is functional in terms of transmiting a signal for clonal deletion.