Proliferative responses of naive CD4 and CD8 T cells after cotransfer of separate transfer. Groups of Rag1^−/− and TCRβ^−/− recipients were transferred with 10⁶ Ly5.1 naive T cells (cotransfer). Another group of mice were transferred with either 0.5 × 10⁶ Ly5.1 naive CD4 or CD8 cells (separate transfer). The total cell recovery as well as the CD4/CD8 ratio in the indicated tissues was analyzed 7 days after transfer. Each symbol represents individual recipient mice. Shown are the mean ± SD of individually tested mice (n = 3-11).