| dc.description.abstract | Introduction: Viral infections and reactivations still remain a
cause of morbidity and mortality after hematopoietic stem
cell transplantation due to immunodeficiency and immunosuppression. Transfer of unmanipulated donor-derived lymphocytes (DLI) represents a promising strategy for improving cellular immunity but carries the risk of graft versus host
disease (GvHD). Depleting alloreactive naïve T cells (TN) from
DLIs was implemented to reduce the risk of GvHD induction
while preserving antiviral memory T-cell activity. Here, we
compared two TN depletion strategies via CD45RA and
CD62L expression and investigated the presence of antiviral
memory T cells against human adenovirus (AdV) and Epstein-Barr virus (EBV) in the depleted fractions in relation to
their functional and immunophenotypic characteristics.
Methods: T-cell responses against ppEBV_EBNA1, ppEBV_
Consensus and ppAdV_Hexon within TN-depleted (CD45RA−/
CD62L−) and TN-enriched (CD45RA+/CD62L+) fractions were
quantified by interferon-gamma (IFN-γ) ELISpot assay after
short- and long-term in vitro stimulation. T-cell frequencies
and immunophenotypic composition were assessed in all
fractions by flow cytometry. Moreover, alloimmune T-cell responses were evaluated by mixed lymphocyte reaction. Results: According to differences in the phenotype composition, antigen-specific T-cell responses in CD45RA− fraction
were up to 2 times higher than those in the CD62L− fraction,
with the highest increase (up to 4-fold) observed after 7 days
for ppEBV_EBNA1-specific T cells. The CD4+ effector memory
T cells (TEM) were mainly responsible for EBV_EBNA1- and
AdV_Hexon-specific T-cell responses, whereas the main
functionally active T cells against ppEBV_Consensus were
CD8+ central memory T cells (TCM) and TEM. Moreover, comparison of both depletion strategies indicated that alloreactivity in CD45RA− was lower than that in CD62L− fraction.
Conclusion: Taken together, our results indicate that CD45RA
depletion is a more suitable strategy for generating TN-depleted products consisting of memory T cells against ppEBV_EBNA1 and ppAdV_Hexon than CD62L in terms of depletion effectiveness, T-cell functionality and alloreactivity. To
maximally exploit the beneficial effects mediated by antiviral memory T cells in TN-depleted products, depletion methods should be selected individually according to phenotype
composition and CD4/CD8 antigen restriction. TN-depleted
DLIs may improve the clinical outcome in terms of infections,
GvHD, and disease relapse if selection of pathogen-specific
donor T cells is not available | en_US |
