Engraftment of donor-derived myeloid cells correlates with a higher CD4⁺ T-cell count (1 year after HSCT and at last follow-up) and higher naive CD4 T-cell counts. FU denotes follow-up. Patients were separated into 2 groups according to their myeloid chimerism: group 1 with host myeloid chimerism and group 2 with donor or mixed myeloid chimerism. (A,B) CD4⁺ T-cell counts 1 year after HSCT and at last follow-up were significantly higher in the group with donor or mixed myeloid chimerism (P < .001 using a Mann-Whitney nonparametric test and P = .03 using a linear regression model). (C) Naive CD4⁺ T-cell counts at last follow-up were significantly higher in the group with donor or mixed myeloid chimerism (P = .04 using a linear regression model). (D) Relation between naive CD4⁺ T-cell counts at last follow-up and at diagnosis. Patients who did not receive a fully myeloablative CR were separated into 2 groups according to their genetic defect: group 1 includes Rag1/2/Artemis-deficient patients and group 2 includes γc/Jak3/IL7Rα deficiencies. Naive CD4⁺ T-cell counts were significantly higher in group 2 (P = .01 using a linear regression model).