Degree of major histocompatibility complex mismatching may be detrimental to B cell functional reconstitution after hematopoietic stem cell transplantation in infants with severe combined immunodeficiency.

BACKGROUND

In addition to the main goal of T cell engraftment, the functional reconstitution of B cell function is an important indicator of successful hematopoietic stem cell transplantation (HSCT) for severe combined immunodeficiency (SCID) patients.

OBJECTIVE

Poor functional reconstitution of B cell function may relate to lower degree of Major Histocompatibility Complex (MHC) compatibility in children with SCID after HSCT.

STUDY

DESIGN

We aimed to analyze the outcomes of HSCT in children with SCID in a referral tertiary center in southern Taiwan. We collected data retrospectively from all seven infants with SCID who received HSCT and were followed-up at the center during 2005-2025.

RESULTS

All patients survived with reconstituted T cells during the follow-up period. One hundred percent T cell engraftment of donor cells are noted in all patients while variable degrees of chimerism were noted in other leukocytes. However, the extent of B cell chimerism does not appear to determine the outcome of B cell functional recovery. Two haploidentical-transplant patients required regular immunoglobulin supplement to prevent frequent infections.

CONCLUSION

Newborn screening for SCID may successfully identified patients with SCID and early HSCT helped them to survive the previously fatal disease. However, poor immunoglobulin recovery requiring lifelong immunoglobulin replacement was observed in the two patients who underwent haploidentical HSCT. Haploidentical transplantation as a potential cause of compromised B cell recovery in SCID treatment should be further investigated.