A functionally rearranged TCRβ (Tcrb) gene was isolated from a cloned human T helper cell recognizing the CS.T3 epitope of Plasmodium falciparum with HLA-DR2. Transgenic mice were generated by co-injection of the human gene together with the mouse Tcrb enhancer. Analysis of transgenic mice shows that the functional Tcrb gene of xenogenic, i.e. human, origin exerts allelic exclusion of endogenous Tcrb genes. Cytofluorometric analysis revealed expression of the human TCRβ chain on virtually all thymocytes and peripheral T cells together with endogenous TCRβ chains and CD3 components. No surface expression of mouse TCRβ chain or rearrangement of endogenous Tcr genes was detectable. Expression of the hybrid receptor causes a reduction in the number of thymocytes and a bias for CD4+CD8− T cells in the thymus as compared with non-transgenic littermates. Peripheral transgenic T cells mount a normal prollferative response against allogenelc targets in mixed lymphocyte reactions. These results show that a hybrid mouse/human TCR is able to pass positive and negative selection in the thymus, and is functional in transgenic mic
