Lymphocyte composition in the spleen and thymus of mice 8 to 12 weeks of age. (A) The percentages of T cells (P = .0372), especially CD8⁺ T cells (P = .001), in the spleen were lower in Phf6 knockout (KO) mice than in Phf6 wild-type mice (wild-type, n = 12; Phf6 KO, n = 12), whereas the B-cell and CD4⁺ T-cell percentages did not differ. (B) Within CD4⁺ splenocytes, Phf6 KO mice had higher percentages of naive regulatory T cells (Treg) (left panel; P = .0076) but lower percentages of effector T cells (right panel; P = .0043; wild-type, n = 12; Phf6 KO, n = 12). (C) Within thymocytes, Phf6 KO mice had lower percentages of CD4 and CD8 double-negative (DN) cells compared with wild-type mice (P = .0316; both, n = 5). *P < .05; **P < .01; ***P < .001. DP, CD4 and CD8 double-positive cells.