Early immune reconstitution is predictive of late immune reconstitution and late thymic output. FU denotes follow-up. (A,B) Early CD4⁺ T-cell counts are predictive of late CD4⁺ and naive CD4⁺ T-cell counts. Patients with follow-up > 5 years were divided in 2 groups according to their CD4⁺ T-cell count 1 year after HSCT. CD4⁺ T-cell counts and naive CD4⁺ T-cell counts at last follow-up were significantly higher in patients with a normal CD4⁺ T-cell count 1 year after HSCT (P ≤ .001 using a linear regression model). (C) Individual CD4⁺ T-cell counts in patients with follow-up of 20 years or longer, showing no decline in CD4⁺ T cells 10 years or more after HSCT.