Antiviral immunity in patients after allogeneic hematopoietic stem cell transplantation during the post-engrafment period
Anna A. Dmitrova, Vyacheslav A. Shmarov, Mikhail Y. Drokov, Larisa A. Kuzmina, Natalia N. Popova, Ekaterina D. Mikhaltsova, Vera A. Vasilyeva, Maria V. Dovydenko, Olga M. Koroleva, Darya S. Dubnyak, Zoya V. Konova, Ekaterina V. Usikova, Ulyana V. Maslikova, Olga S. Starikova, Dmitry O. Kiryukhin, Grigoriy A. Efimov, Elena N. Parovichnikova, Valery G. Savchenko
National Medical Research Center of Hematology, Moscow, Russia
Contact: Dr. Anna A. Dmitrova
E-mail: dr.admitrova@gmail.com
Summary
Cytomegalovirus (CMV) is a common virus that persists asymptomatically in 70-90% of healthy population. CMV infection is one of most frequent infectious complications in patients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Despite treatment of CMV infection with antiviral drugs, CMV reactivation remains a major problem because it reduces the overall survival of patients after allo-HSCT.
Materials and methods
We analyzed cytotoxic T-lymphocytes (CTLs) in peripheral blood of 39 patients on day +30 after allo-HSCT. Leukocyte cell suspension after preliminary red blood cells lysis were incubated with a protein tyrosine kinase inhibitor (Dasatinib) for 1 hour at 37°С in order to increase surface expression of both TCR and CD8. CMV-specific CTLs were identified by flow cytometry using fluorochrome-labeled monoclonal antibodies against CD3, CD8, CD45 molecules, viability reagent and tetramers consisting of in-house produced MHC class I monomers loaded with one of two immunodominant epitopes of viral pp65 protein (NLVPMVATV (NLV) and TPRVTGGGAM (TPR) peptides that are present in HLA-A*02 and -B*07 antigens, respectively, bound to phycoerythrin-conjugated streptavidin. Two-platform method was used to calculate absolute CMV (NLV/TPR)-specific CD3+CD8+ cell counts in peripheral blood. The patients subjected to allo-HSCT included in the analysis were HLA-A*02- (n=22), HLA-B*07- (n=11), or HLA-A*02-B*07-positive (n=6). Their clinical and transplant characteristics are presented in Table 1.
Results
Figure 1 shows the number of CMV-specific T cells at the day +30 after allo-HSCT in patients with various modes of GVHD prophylaxis. Patients with more “aggressive” GVHD prophylaxis regimens (based on the use of high doses of post-transplant cyclophosphamide, T-cell depletion) have less CMV-specific T cells at +30 days after allo-HSCT.
Conclusion
The patients with “aggressive” GVHD prophylaxis are the most likely candidates for cell therapy. The use of prophylactic infusion of selected lymphocytes (CD45RA- fraction, CMV-specific T-lymphocytes) probably can improve the reconstitution of antiviral immunity, reduce the frequency of reactivation and increase overall survival in these categories of patients.
Keywords
Allogeneic hematopoietic stem cell transplantation, cytomegalovirus, antiviral drugs, adoptive cellular therapy, CMV-specific T cells.
Figure 1. The number of CMV-specific T cells depending on the GVHD prophylaxis at 30 days after allo-HSCT
The green color indicates patients who additionally underwent prophylactic infusion of the CD45RA- fraction at day 0. The “dot plot” shows the results of the study of CMV-specific T cells in one of the patients with T-depletion at +30 days after HSCT.
Table 1. Clinical characteristics of the patients
