Abstract
Background aims. Varicella zoster virus (VZV) causes life-long latent infection in healthy individuals, which reactivates in 10–68% of stem cell transplant patients. Reconstituting immunity through adoptive transfer of T cells specific for VZV may aid in the prophylaxis and treatment of VZV infections. The potential for generating T cells specific for VZV using a clinically approved VZV vaccine strain was investigated. Methods. The Varivax® vaccine was used to stimulate peripheral blood mononuclear cells from healthy donors. Only reagents approved for clinical manufacture were used. Monocyte-derived dendritic cells pulsed with Varivax (R) were used to stimulate autologous mononuclear cells at a responder to stimulator ratio of 10:1. On day 7, a second stimulation was performed; 20 U/mL interleukin (IL)-2 were added from day 7 and 50 U/mL IL-2 from day 14 onwards. Cell phenotype and functionality were assessed after 21 days of culture. Results. A mean increase of 11-fold in cell number was observed (n= 18). Cultures were mainly T cells (mean CD3 + 89.7%, CD4 + 54.2%, CD8 + 28.7%) with effector and central memory phenotypes. Cells produced one or more T helper (Th)1 cytokine (interferon-γ, tumor necrosis factor-α and IL-2), and CD4 + (but not CD8 + ) cells expressed the cytoxicity marker CD107 when restimulated with VZV antigens. Conclusions. We have demonstrated a clinically applicable method that yields high numbers of highly reactive T cells specific for VZV. We propose that reconstructing host immunity through adoptive transfer of VZV-specific T cells will reduce the frequency of clinical VZV infection in the period of severe immune suppression that follows allogeneic stem cell transplantation.
Acknowledgements
We gratefully acknowledge the support of the following funding bodies. The Cancer Council of NSW (grant ID RG 09-07). EB is a Leukaemia Foundation of Australia Clinical Fellow, a NSW Cancer Institute Research Scholar (RSA07 - 1–02) and a recipient of the Royal Australasian College of Pathologists Research Award.
Authorship contributions: EB designed and performed the experiments, performed the data analysis and wrote the manuscript; SG assisted with collection and processing of blood and performed some of the experiments; LC assisted with the design of the experiments and analysis of data and performed some experiments; RS performed some of the experiments and assisted with laboratory procedures; IB performed some of the experiments and performed some data analysis; KM assisted with the analysis of data and preparation of the manuscript; and DG provided overall academic leadership, and assisted with the design of the experiments, analysis of data and preparation of the manuscript.
Disclosure of interests: Varivax for use in these experiments was provided as a gift from CSL Inc. CSL Inc. did not have any involvement in the experimental design, interpretation of results or preparation of the manuscript.