Abstract Introduction The immune reconstitution (IR) after the allogenic hematopoietic stem cell transplantation (allo-HSCT) is a progressive process intrinsically correlated to the therapeutic 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 allogeneic 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/μL, 1022/μL and 1541/μL, 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 conditioning, 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 ≥ 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 ≥ 500/μL on D+100 was a simple IR predictor of survival, easily available to resource-limited centers.

O transplante de células-tronco hematopoéticas (TCTH) é o tratamento de escolha para leucemias agudas de alto risco. Apesar da melhora na sobrevida destes pacientes, a recidiva continua sendo a maior causa de óbito pós-transplante de células-tronco hematopoéticas. O objetivo deste trabalho foi analisar os resultados dos transplantes realizados em crianças com leucemia aguda em duas instituições brasileiras. Realizou-se estudo retrospectivo de 208 pacientes transplantados entre 1990-2007. Mediana de idade: 9 anos; 119 pacientes com leucemia linfoide aguda (LLA) e 89 com leucemia mieloide aguda (LMA). Doença precoce: CR1 e CR2. Doença avançada: >CR3, doença refratária ou recidivada. Noventa pacientes vivos entre 258-6.068 dias (M:1.438), com sobrevida global (SG) de 45% (3 anos) e a sobrevida livre de recaída (SLR) 39% (três anos). 14/195 pacientes tiveram falha primária de pega (8%). Não houve diferença na sobrevida global e sobrevida livre de recaída entre pacientes com leucemia linfoide aguda e leucemia mieloide aguda, entre transplantes aparentados e não aparentados, tampouco entre as fontes de células utilizadas. O desenvolvimento da doença do enxerto contra hospedeiro (DECH) aguda ou crônica também não influenciou a sobrevida global e sobrevida livre de recaída. Pacientes com leucemia linfoide aguda condicionados com irradiação corporal total (TBI) apresentaram melhor sobrevida global e sobrevida livre de recaída (p<0,001). Cento e dezoito pacientes morreram entre 1-1.654 dias pós-transplante de células-tronco hematopoéticas (M:160). Mortalidade relacionada a transplante (MRT) (dia+100): 16%. Incidência cumulativa de recaída: 40% (3 anos). Pacientes com doença avançada tiveram menor sobrevida global e sobrevida livre de recaída (três anos)(p<0,001). Na análise multivariada, o status da doença foi o principal fator associado ao aumento da sobrevida global e sobrevida livre de recaída. Nossos resultados mostram que é possível se atingir uma boa sobrevida para pacientes com doença precoce e também mostram a baixa eficácia naqueles com doença avançada.

Hematopoietic Stem Cell transplantation (HSCT) is the treatment of choice for patients with high-risk leukemia. In spite of this, relapse remains a major cause of death of these patients. Our objective was to analyze the outcomes of patients with acute leukemia submitted to hematopoietic stem cell transplantation in two Brazilian institutions. A retrospective study of 208 patients transplanted between 1990 and 2007 with a median age of 9 years (range: 1-18 years) was made. One hundred and nineteen patients had acute lymphocytic leukemia (ALL) and 89 had acute myeloid leukemia (AML). Early disease was considered for CR1 and CR2 cases and advanced disease >CR3 and refractory and relapse disease. Ninety patients are alive between 258 and 6068 days after hematopoietic stem cell transplantation (M: 1438 days). The overall survival (OS) was 45% (3 years) and event free survival (EFS) was 39% (3 years). Primary graft failure occurred in 14/195 patients (8%). There were no differences in the overall survival and event free survival between patients with acute lymphocytic leukemia and acute myeloid leukemia, between sources of cells used or between those who developed acute or chronic graft-versus-host disease (GVHD). When comparing transplants from related and unrelated donors, there was no difference in the overall survival. Patients with acute lymphocytic leukemia receiving the total body irradiation (TBI) conditioning regimen had better overall survival and event free survival (p<0.001). One hundred and eighteen patients died between 0 and 1654 days after hematopoietic stem cell transplantation (M: 160 days). Transplantation-related-mortality (TRM) at D+100 was 16% and cumulative incidence of relapse was 40% (3 years). Patients with advanced disease had lower 3-year overall survival and event free survival (p<0.001). Multivariate analysis showed that disease status was the most significant factor associated with higher event free survival and overall survival . Our results show that children and adolescents transplanted with early disease can achieve considerable overall survival and also highlights the inefficacy of hematopoietic stem cell transplantation for patients with advanced disease.