Positive selection of class II–restricted TCR is reduced in the MKK3(A)/MKK6(A) transgenic mice.

Thymocytes (panel A) and splenocytes (panel B) from AND TCR transgenic mice and AND × MKK3(A)/MKK6(A) transgenic mice were analyzed for CD4 and CD8 expression. The percentages represent the fraction of each subpopulation in a total thymocyte or splenocyte population. The average cell number and SD of each thymic and splenic subpopulation from 6 pairs of mice are indicated. (C) Expression of Vβ3 in lymph node cells from AND mice and AND × MKK3(A)/MKK6(A) mice. The percentage represents the fraction of the CD4⁺Vβ3⁺ population in the lymph node cells. The number indicates the average cell number of CD4⁺Vβ3⁺ lymph node cells from 6 pairs of mice. (D) Expression of CD69 in thymocytes from AND mice and AND × MKK3(A)/MKK6(A) mice. The percentage shown represents the fraction of the CD69⁺ population in the total thymocytes, whereas the number indicates the average cell number of CD69⁺ lymph node thymocytes (± SD) from 6 pairs of mice.