Immune reconstitution in children after haploidentical haematopoietic stem cell transplantation

Area of Science:

• Immunology
• Hematology
• Pediatric Oncology

Background:

• Immune reconstitution (IR) kinetics in pediatric patients undergoing haploidentical hematopoietic stem cell transplantation (HSCT) with post-transplant cyclophosphamide (PTCy) require further investigation.
• Comparison of IR patterns between haploidentical and HLA-matched HSCT in children is essential for understanding post-transplant outcomes.

Purpose of the Study:

• To compare immune reconstitution patterns in pediatric patients after haploidentical HSCT with PTCy versus HLA-matched HSCT.
• To identify risk factors for viral infections in these pediatric HSCT recipients.

Main Methods:

• Prospective measurement of lymphocyte subsets before and up to 12 months after HSCT.
• Monitoring of viral loads for cytomegalovirus (CMV), Epstein-Barr virus, adenovirus, and BK virus (BKV) in blood and urine.

Main Results:

• Haploidentical HSCT recipients exhibited significantly lower median counts of T cells and T helper cells at 1 month post-HSCT compared to HLA-matched recipients.
• Delayed recovery of T cell subsets and B cells was observed in the haploidentical group throughout the first year.
• Increased incidence of BKV hemorrhagic cystitis, blood CMV, and urine adenovirus reactivation was noted in the haploidentical group. Addition of anti-T lymphocyte globulin (ATG) further delayed T cell recovery and increased BKV reactivation.

Conclusions:

• Pediatric haploidentical HSCT with PTCy is associated with delayed immune reconstitution and a higher risk of viral reactivation compared to HLA-matched HSCT.
• The use of ATG in conjunction with PTCy exacerbates T cell recovery delay and elevates the risk of BKV reactivation.