Donor-derived postthymic T cells express a diverse Vβ repertoire. A cell suspension containing 6 × 10⁷ B6.SJL T cells was injected into unirradiated B6AF1 recipients. Three-color staining was performed using the following antibodies: FITC-labeled anti-Vβ, Cy-chrome–labeled anti-CD4 or anti-CD8, and biotin-coupled anti-Ly5.1 plus Streptavidin-PE. Chimeras were studied on day +12. Results are presented as the mean ± SD (3 mice per group). *P< .05 when compared with B6.SJL controls.