Abstract
Background aims. Influenza viruses cause potentially fatal respiratory infections in stem cell transplant patients. Specific T cells provide long-lived host adaptive immunity to influenza viruses, and the potential for generating such cells for clinical use was investigated. Methods. The inactivated influenza vaccine (Fluvax) approved for human use was used as the antigen source. Monocyte-derived dendritic cells pulsed with Fluvax were used to stimulate autologous peripheral blood mononuclear cells (PBMC) on days 0 and 7. Cells were expanded with interleukin (IL)-2 from day 7 onwards. Cell numbers and phenotype were assessed on day 21. The presence of influenza virus-specific cells was assessed by cytokine production and proliferative responses following restimulation with influenza antigens. Results. Over 21 days of culture, a mean fold increase of 26.3 in cell number was observed (n = 7). Cultures were predominantly effector and central memory CD4+ cells, and expressed a phenotype characteristic of activated antigen-specific cells capable of B-cell helper function. Cytotoxic CD4+ and CD8+ cells specific for influenza and a high percentage of CD4+ cells specific for each of three influenza viruses targeted by Fluvax (H1N1, H3N2 and Brisbane viruses) were generated. In addition, T cells expanded when restimulated with antigens derived from influenza viruses. Conclusions. We have demonstrated a clinically usable method for producing influenza virus-specific T cells that yield high numbers of highly reactive CD4+ cells suitable for adoptive immunotherapy. We propose that reconstructing host immunity through adoptive transfer of influenza virus-specific T cells will reduce the frequency of influenza-related deaths in the period of severe immune suppression that follows stem cell transplantation.
Acknowledgments
We wish to thank Professor Dominic Dwyer and Dr Stuart Tangye for helpful discussion and advice, and Dr Kenneth Micklethwaite for reviewing this manuscript.
Author contributions: SG assisted with the design of experiments, performed experiments and data analysis and wrote the manuscript. LC and EB had intellectual input, assisted with the design of experiments and data analysis. EB and RS performed some of the experiments and assisted with laboratory procedures. CM assisted with some of the experiments. DG originated the project, gave overall academic leadership, assisted with experiment design and edited the manuscript.
Conflict of interest: The authors disclose no conflict of interest.