Naive T cells in Tgfb2^+/- mice. Fraction of naive (CD44^lowCD45RB⁺) cells of the CD4 and CD8 populations in the peripheral blood of 8-week-old (A) and 12-month-old (B) Tgfb2^+/- mice and wt littermates. Each connected pair of data points represents the average of 2 to 4 Tgfb2^+/- and wt members of a litter.