Donor CD3⁺ T-cell, CD19⁺ B-cell, and myeloid chimerism vs conditioning regimen intensity (RIC vs MAC) over the first 2 years after HCT. Donor chimerism: full, >95%; high-level, 50% to 95%; low-level, 5% to 49%; rejection, <5%. MAC resulted in a higher percentage of patients with full donor (>95%) CD3⁺ T-cell chimerism compared with RIC at day 100 (P < .001), 6 months (P = .006), and 1 year (P = .002) after HCT. This difference was not significant at 2 years after HCT. MAC resulted in a higher percentage of patients with full donor (>95%) B-cell chimerism at day 100 (P = .004) and myeloid chimerism at 6 months (P = .023), compared with RIC. The differences at all other time points were not significant.