Reconstitution of adaptive immunity after umbilical cord blood transplantation: impact on infectious complications

Abstract

In comparison with allogeneic stem cell transplantation (alloHSCT) with other stem cell sources, umbilical cord blood transplantation (UCBT) was traditionally associated with increased risk of infections, particularly during the first 3 months after transplantation. Longitudinal studies of immune monitoring reported peculiar patterns of T-and B-cell recovery in the peripheral blood of UCB recipients during the first months post-transplantation. Overall, current data suggest delayed reconstitution of naive and memory CD4+ and CD8 + T-cell pools after UCBT. This is particularly true for adult recipients and for patients who received in vivo T-cell depleting approaches before the transplantation. Such delayed T-cell recovery may increase susceptibility of UCB recipients for developing opportunistic infections and viral reactivations.Regarding B-cell recovery, UCBT was associated with accelerated B-lymphopoiesis. Recent studies also reported evidence for faster functional memory B-cell recovery in UCB recipients. In this article, we briefly review T-and B-cell reconstitution after alloHSCT, with emphasis on peculiarities observed after UCBT.We further put these data in lines with risks of infections after UCBT.

Clinical Relevance of Immunobiology in Umbilical Cord Blood Transplantation

“…T cell reconstitution is delayed after UCBT as compared to bone marrow transplantation (BMT) [30] and peripheral blood stem cell transplantation (PBSCT) [31]. T cell reconstitution after HCT occurs in two distinct pathways: (1) Peripheral expansion of mature T cells (thymus-independent pathway), and (2) thymopoiesis from donor hematopoietic progenitors (thymus-dependent pathway) [32,33]. Early after HCT, T cell reconstitution takes place through peripheral expansion by T cells transferred from the graft or recipient T cells which have survived conditioning therapy ( thymus-independent pathway ).…”

Child with Wiskott–Aldrich syndrome underwent atypical immune reconstruction after umbilical cord blood transplantation: a case report

“…In general, innate immunity, namely phagocytes and natural killer lymphocytes, recovers in the first few weeks after transplantation. Then, the adaptive immune system, namely B and T lymphocytes, recovers, which may take months to years[7,9,16,20]. Reconstitution of CD4 + T cells is later than that of CD8 + T cells, which in most cases also results in a long period of CD4 + /CD8 + inversion after transplantation.…”

“…Innate immunity usually recovers within several weeks after transplantation. By contrast, adaptive immunity recovers more slowly[5-7]. This delayed engraftment and immune reconstitution result in higher rates of early post-transplantation infection complications in UCBT[8,9].…”

Umbilical cord blood: The promise and the uncertainty

“…UCB is associated with increased risk of infectious complications especially in the first 100 days after transplant 22‐24 . After UCB transplant, there is a delayed recovery of naïve and memory T cells, thus increasing the risk of opportunistic infections and viral reactivations 22 . Karantanos et al evaluated the development of BK viremia and the immune recovery after UCB transplant.…”