Plasma IL-7 levels, Ki67 expression, and TRECs after thymectomy during infancy. (A) Plasma IL-7 levels in the first 2.5 years after thymectomy (TX, n = 14) compared with age-matched healthy controls (HC, n = 16). Asterisk denotes statistical significance; horizontal line represents median value for each group. (B) Correlation between plasma IL-7 levels and the number of naive CD4⁺ T cells per microliter of blood in thymectomized individuals during the first 2.5 years after thymectomy (n = 11). The percentage of proliferating (Ki67⁺) cells in the naive CD4⁺ (C) and naive CD8⁺ (D) T-cell populations in the first 5 years after thymectomy compared with healthy age-matched controls. Lines connect longitudinal samples. (E) Percentage of proliferating (Ki67⁺) cells (median value + SD) in the naive CD4⁺ and naive CD8⁺ T-cell populations in thymectomized individuals from 5 years after thymectomy onward (n = 9) compared with age-matched healthy controls (n = 47). Average TREC content of CD4⁺ T cells (F) and the total number of CD4⁺ T-cell TRECs per microliter of blood (G) in thymectomized individuals and healthy controls as a function of age. ▴ represents values after thymectomy; ▵, samples taken just before thymectomy; and ○, healthy controls. Lines connect longitudinal samples.