INTRODUCTION
Allogeneic hematopoietic stem cell
transplantation (allo-HSCT) is a potential treatment for many patients
with malignant and non-malignant diseases. Although much improvement has
been made during the past decades, several complications affecting
patient survival or quality of life remain to be addressed.1
It is well established that immune reconstitution (IR) after HSCT is
influenced by patient and transplant factors and strongly associated
with transplant outcomes. 2 Disease type, recipient
age, source of the stem cells, type of donor, conditioning regimen, use
of serotherapy, prophylaxis and treatment for graft-versus-host disease
(GvHD) and viral infections may have a major impact on IR.3–8 Despite numerous studies, predictive immune
parameters of clinical outcomes remains elusive due to the variety of
cut-off values for lymphocyte counts, time post-HSCT for samples
collections, and the group of patients included in each study.4
There is a dearth of studies regarding IR after pediatric HSCT,
especially for patients transplanted in resource-limited countries. In
many places around the world, socioeconomic problems, availability of
well-matched donors, lack of drugs and tests limit access to this
curative procedure. These barriers culminate in a lower volume of HSCT,
and consequently in lower number of publications on this topic compared
with North America and Europe. 9
Our objective was to analyze the absolute lymphocyte count (ALC) and
lymphocyte subpopulations after HSCT and correlate these factors with
transplant characteristics and post-transplant endpoints, such as
overall survival, acute GvHD (aGvHD), cytomegalovirus (CMV) infection,
and death.