Selection of class I–restricted transgenic TCR is decreased in MKK3(A)/MKK6(A) transgenic mice.

(Panel A) Thymocytes from H-Y TCR transgenic mice and H-Y × MKK3(A)/MKK6(A) transgenic mice were analyzed for CD4 and CD8 expression. The percentage represents the fraction of that subpopulation in a total thymocyte population. The average cell number and SD of each thymic subpopulation from 4 pairs of mice are indicated. (B) Thymocytes were also analyzed for expression of Vβ8 in the CD8⁺ fraction. The percentage of Vβ8⁺cells in CD8⁺ thymocytes and the average cell number (± SD) of CD8⁺Vβ8⁺ thymocytes from 4 pairs of mice are indicated. (C) CD69 expression in thymocytes from H-Y mice and H-Y × MKK3(A)/6(A) mice. The percentage and average cell number of CD69⁺ thymocytes are indicated. (D) The CD69⁺ thymocyte population was gated, and the fractions of CD4⁺CD8⁺, CD4⁺CD8⁻, and CD4⁻CD8⁺ were determined.