This transgene contains the following elements: the immunoglobulin kappa (Igk) chain promoter, rearranged Igk-V and -J segments, including leader and intron, from the KL25 hybridoma against the lymphocytic choriomeningitis virus (LCMV) WE strain, the Igkc light chain kappa constant domain segment, IRES sequence, a Thy1/Pdgfrb fusion gene (ectodomain of the Thy1 marker gene fused to the transmembrane domain of the mouse Pdgf receptor), and an Igk enhancer element. (J:306923)