Immune Reconstitution in Pediatric Patients Post Autologous Stem Cell Transplantation.

OBJECTIVES

To determine the prevalence of hypogammaglobulinemia at three months post-ASCT and characterize humoral and cellular immune reconstitution kinetics.

METHODS

Twelve pediatric patients (median age 10 y) undergoing ASCT for high-risk neuroblastoma (n = 4) or relapsed / refractory Hodgkin lymphoma (n = 8) at AIIMS New Delhi (February 2024-November 2025) were prospectively followed. Serial immunoglobulin levels and lymphocyte subsets were measured at baseline and on days +15, +30, +90, +180. Linear mixed-effects models analyzed trajectories on percentages and absolute counts.

RESULTS

Median IgG at day +90 was 1070 mg/dL (IQR 901-1244). Hypogammaglobulinemia (IgG <500 mg/dL) occurred in 2 of 12 patients (16.7%; 95% CI: 2.1-48.4); both had received rituximab pre-transplant. None of the nine rituximab-naïve patients developed hypogammaglobulinemia. IgM showed a non-significant upward trend at day +90 (p = 0.054), reaching significance at day +180 (p <0.05). Absolute-count analysis demonstrated CD8+ expansion at day +30 (Δ = +652 cells/µL; p = 0.001), profound B-cell depletion at days +15 and +30 (both p <0.01), and a CD4+ deficit at day +90 (Δ = -198 cells/µL; p = 0.017). NK-cell counts remained stable.

CONCLUSIONS

Pediatric ASCT recipients demonstrated predictable immune recovery; hypogammaglobulinemia at three months was confined to rituximab-exposed patients, supporting risk-stratified post-transplant immunoglobulin surveillance and revaccination.