Transgenic TCR expression selects CD4+ T cells in the thymi of BDC2.5/NOD.scid mice. Three-color flow cytometric analysis of thymi from negative littermate (NOD.scid/+; Left), TCR transgenic (BDC2.5/NOD.scid/+; Center), and TCR/NOD.scid transgenic (BDC2.5/NOD.scid; Right) mice was performed using anti-CD4, anti-CD8α, and anti-Vβ4 TCR mAb. (Upper) Two-color dot plots of CD4 versus CD8. (Lower) Vβ4 TCR expression on gated CD4+CD8− (CD4+), CD4+CD8+ (DP), CD4−CD8+ (CD8+) and CD4− CD8− (DN) subpopulations.