CD8A and Splenomegaly: In addition to reduced body weight, old but not young Tdrd3-deficient Treg mice also exhibited splenomegaly (Fig. 4B), with markedly increased spleen weight (Fig. 4C) and total cellularity (Fig. 4D), together with an increased CD3+ T cells, including both CD4+ and CD8+ subsets (Fig. 4E).