Immune reconstitution after allogenic stem cell transplantation: An observational study in pediatric patients

Introduction: The immune reconstitution (IR) after the allogenic hematopoietic stem cell transplantation (allo-HSCT) is a progressive process intrinsically correlated to the thera-peutic success. It is essential to understand the interfering factors in IR to prevent the HSCT-related mortality.Methods: We retrospectively evaluated the clinical outcomes, absolute lymphocyte counts (ALCs) and lymphocyte subtypes at different time-points of 111 pediatric patients with allo-geneic HSCT for malignant and non-malignant diseases from 2013 to 2018. Results: The ALCs gradually increased on D+30, D+100, and D+180 (medians 634/mL, 1022/mL and 1541/mL, respectively). On D+100, the CD3+CD8+ achieved the highest recovery rate (68%), followed by the CD16+CD56+ (47%), CD3+CD4+ (39%) and CD19+ (8%). The adequate ALC recovery was associated with age < 8 years, bone marrow grafts, myeloablative condi-tioning, non-use of serotherapy and non-haploidentical donors. The ALC and CD3+CD8+ on D+100 counts were higher in patients with the cytomegalovirus infection. The CD3+CD4 + recovery was associated with an age < 8 years, a non-malignant disease and a lower incidence of acute graft-versus-host disease & GE; grade 2. Furthermore, the ALC recovery on D +100 resulted in a higher overall survival, regardless of the disease type (HR 3.65, 1.05 -12.71, p = 0.04).Conclusion: Several factors influenced the IR after the allo-HSCT. The ALC & GE; 500/mL on D+100 was a simple IR predictor of survival, easily available to resource-limited centers.& COPY; 2022 Associacao Brasileira de Hematologia, Hemoterapia e Terapia Celular. Published by Elsevier Espana, S.L.U.This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).