CD4⁺CD25⁺ thymocytes are severely decreased in DO10⁺TCRα^−/− mice in positively selecting and negatively selecting backgrounds.

(A, B) Thymocytes from DO10⁺ mice (H-2^d/d), DO10⁺ TCRα^−/− mice (H-2^d/d), and DO10⁺ TCRα^−/−mice (H-2^b/b) were stained with KJ1-26 FITC, anti-CD25 PE, anti-CD8 APC, and anti-CD4 PerCP. Shown are representative FACS profiles of CD4 versus CD8 on total thymocytes (A) and CD4 versus CD25 on CD4⁺ CD8⁻ KJ1-26^high thymocytes (B) from 5 mice in each group. The numbers of thymocytes are as follows: DO10⁺ TCRα^+/+H-2^d/d mice (10.8 ± 2.6 × 10⁷), DO10⁺ TCRα^−/− H-2^d/d mice (13.2 ± 3.0 × 10⁷), and DO10⁺TCRα^−/− H-2^b/b mice (0.6 ± 0.2 × 10⁷) (n = 5 mice each;P < .01). (C) Splenocytes from DO10⁺H-2^d/d mice, DO10⁺ TCRα^−/−H-2^d/d mice, and DO10⁺ TCRα^−/−H-2^b/b mice were stained with anti-CD25 PE and anti-CD4 FITC. Shown are representative FACS profiles of CD4 versus CD25 on splenocytes from 5 mice in each group.