REAL-LIFE DATA ON IMMUNE RECONSTITUTION AFTER ALLOGENIC STEM CELL
TRANSPLANTATION: AN OBSERVATIONAL STUDY IN PEDIATRIC PATIENTS
Abstract
Background: Immune reconstitution (IR) after allogenic hematopoietic
stem cell transplantation (allo-HSCT) is a long and progressive process
intrinsically correlated to therapeutic success. It is essential to
understand interfering factors in IR to prevent HSCT-related mortality.
Methods: We retrospectively evaluated absolute lymphocyte count (ALC)
and lymphocyte subtypes of 111 pediatric patients with allogeneic HSCT
for malignant and non-malignant diseases from 2013 to 2018. ALC recovery
on day +30 (D+30), +100 (D+100) and +180 (D+180) and subtypes CD3+CD4+,
CD3+CD8+, CD19+ and CD16+CD56+ on D+100 were correlated to the HSCT
procedure, clinical outcomes, and survival. Results: ALC had a gradual
increase on D+30, D+100 and D+180 (medians 634/μL, 1 022/μL and 1
541/μL, respectively). On D+100, CD3+CD8+ achieved the highest recovery
rate (68%), followed by CD16+CD56+ (47%), CD3+CD4+ (39%) and CD19+
(8%). Adequate ALC recovery on D+30 was associated with age
<8 years, bone marrow grafts, myeloablative conditioning, and
non-haploidentical donors. The use of serotherapy correlated to a poor
ALC recovery on D+180. Counts of ALC and CD3+CD8+ on D+100 were higher
in patients with cytomegalovirus infection. CD3+CD4+ recovery was
associated with age <8 years, non-malignant disease and a
lower incidence of acute graft-versus-host disease ≥grade 2. Further,
ALC and CD3+CD4+ recovery on D+100 resulted in higher overall survival,
as ALC was determinant regardless of disease type (HR 3.65, 1.05-12.71,
P=0.04). Conclusion: Several factors influenced IR after allo-HSCT.
ALC≥500/μL on D+100 was found to be a simple IR biomarker and a good
predictor of survival, easily available to resource-limited countries.