Negative selection occurs normally in pIV^−/− mice.

Vβ5, Vβ11, and Vβ8 subsets of CD4⁺ and CD8⁺ T cells were analyzed by FACS of splenocytes extracted from pIV^−/− mice and control pIV^+/−littermates. The numbers indicated alongside the bar graphs represent the percentages of the indicated Vβ family relative to the total CD4⁺ (A) or CD8⁺ (B) T-cell populations. White and filled bars represent the mean value (2 to 4 mice) for a nondeleting (I-E⁻) and a deleting (I-E⁺) background, respectively. (C) Representative FACS analysis showing the CD4 and CD8 populations in B10BR thymuses and lymph nodes. B10BR controls (I-E+ I-A+ pIV^+/−, on the left) are compared with B10BR pIV^−/− mice (I-E+ I-A+ pIV^−/− , on the right).