Deficiency in peripheral naïve T cells in Mcl1^ΔFoxn1mice. (A) Graphs show the numbers of CD4⁺ and CD8⁺ T cells gated on splenic TCRβ⁺. Flow cytometry plots of CD44 vs CD62L gated on splenic TCRβ⁺CD4⁺ (B) or TCRβ⁺CD8⁺ (C) T cells. Graphs show the numbers of naïve (CD44^low/CD62L^high), effector (CD44^high/CD62L^low), and central memory (CD44^high/CD62L^high) TCRβ⁺CD4⁺ (B) or CD8⁺ (C) from controls and Mcl1^ΔFoxn1 mice. (D) Graphs show the proportions of proliferating (Ki67⁺) CD4⁺ and CD8⁺ T cells from controls and Mcl1^ΔFoxn1 mice at indicated ages. (E) Graphs show the proportions of splenic Treg cells from controls and Mcl1^ΔFoxn1 mice at the indicated time points. Graph bars indicate mean ± SEM and groups were compared with a Student t test (2 sided, unpaired). *P < .05; **P < .01; ***P < .001; ****P < .0001. Controls include various combinations of genotypes (Foxn1^Cre/+Mcl1^+/+, Foxn1^+/+Mcl1^lox/+, Foxn1^+/+Mcl1^lox/lox, Foxn1^Cre/+Mcl1^lox/+) that showed no differences from each other in separate experiments (n ≥ 3/group).