This transgene is derived from T cell hybridoma line BL17 which encodes the rearrangement Vbeta12-Dbeta1.1-Jbeta1.1 and Cbeta1. The transgene construct was injected into SWR/J fertilized embryos and the mouse line used in this study is referred to as SWR-betaL Tg. This line carries 10 copies of the transgene insertion and expresses high levels of Tcrb mRNA in the spleen.