Host T cells in TCR^–/– → F1 bone marrow chimeras represent a polyclonal population. RT-PCR amplification was performed on total RNA extracted from the spleens of TCR^—/— → F1 and B6 → F1 chimeras. Lanes 1 to 4 represent results for 4 individual TCR^—/— → F1 mice and lanes 5 to 6 are amplification products for 2 individual B6 → F1 mice. Amplification products for Vβ families 1 to 16 are shown. As a control, primers for constant regions of Vβ were used and are denoted as “C.” Results are representative of 2 independent experiments.