Immune reconstitution after double umbilical cord blood stem cell transplantation: comparison with unrelated peripheral blood stem cell transplantation

摘要

Double umbilical cord blood (DUCB) transplantation is an accepted transplantation strategy for patients without suitable human leukocyte antigen (HLA)-matched donors. However, DUCB transplantation is associated with increased morbidity and mortality due to slow recovery of immunity and a high risk of infection. To define the differences in immune reconstitution between DUCB transplantation and HLA-matched unrelated donor (MUD) transplantation, we performed a detailed, prospective analysis of immune reconstitution in 42 DUCB recipients and 102 filgrastim-mobilized unrelated peripheral blood stem cell recipients. Reconstitution of CD3 T cells was significantly delayed in the DUCB cohort compared with the MUD cohort for 1–6 months post-transplantation (p<0.001), including naive (CD45RO−) and memory (CD45RO+) CD4 T cells, regulatory (CD4CD25) T cells, and CD8 T cells. In contrast, CD19 B cells recovered more rapidly in the DUCB cohort and numbers remained significantly greater from 3–24 months after transplantation (p=0.001). CD56CD16 natural killer (NK) cells also recovered more rapidly in DUCB recipients and remained significantly greater from 1–24 months after transplantation. B cell activating factor (BAFF) levels were higher in the DUCB cohort at 1 month (p<0.001), were similar in both cohorts at 3 and 6 months, and were lower in the DUCB cohort at 12 months (p=0.002). BAFF/CD19 B cell ratios were lower in the DUCB cohort at 3 (p=0.045), 6 (p=0.02), and 12 months (p=0.002) after transplantation. DUCB recipients had more infections within the first 100 days after transplantation (p<0.001), and there was less chronic graft-versus-host disease (cGVHD) (p<0.001), but there were no differences in cumulative incidence of relapse, non-relapse death, progression-free survival or overall survival between the two groups. These results suggest that increased risk of infections is specifically associated with delayed reconstitution of all major T cell subsets, but the increased risk is limited to the first 3 months after DUCB transplantation. There is no increased risk of relapse suggesting that graft-versus-leukemia (GVL) activity is maintained. Early reconstitution of B cells and NK cells may, in part, account for these findings.