Correlation between TRECs and either donor myeloid chimerism or diagnosis. (A) Patients were separated into 2 groups according to their myeloid chimerism: group 1 with donor myeloid chimerism and group 2 with host myeloid chimerism. TREC analysis showed significantly higher values in the “Donor” group than in the “Host” group (P = .014). (B) The relationship between myeloid chimerism and the conditioning regimen. Percentages of donor myeloid cells (on the y-axis) were plotted against the busulphan dose (Bu = 0; Bu = 8 mg/kg or Bu > 16 mg/kg). There was a significantly higher number of patients with donor myeloid cells in the group having received full myeloablative treatment (Bu = 16 or 20 mg/kg; P < .001). (C) TREC values (on the y-axis) were analyzed as a function of the intensity of the conditioning regimen (Bu = 0; Bu = 8 mg/kg or Bu > 16 mg/kg). The differences between the 3 groups were not significant (P = .15). (D)l The relationship between TREC⁺ T-cell status and diagnosis. Patients who did not receive a fully myeloablative CR (n = 24) were separated into 2 groups according to their genetic defect: γc deficiency and others (γc⁺). The difference between the 2 groups was not significant (P = .06).