Defining novel parameters for the optimal priming and expansion of minor histocompatibility antigen-specific T cells in culture.
BACKGROUND
Adoptive transfer of minor histocompatibility antigen (MiHA)-specific T cells is a promising therapy for patients with hematological cancers. However, the efficacy of the transferred cells is hampered by the acquisition of terminal effector differentiation and exhaustion features during expansion in vitro thus preventing their function and persistence in vivo. Yet, the factors that induce T-cell differentiation and functional impairment in culture remain poorly defined and are likely to vary depending on the method used for expansion.


METHODS
Using the clinically relevant HLA-A0201-restricted MiHA HA-1 as well as reagents and procedures that are readily transferable to a clinical environment, we designed a novel culture protocol and defined how exhaustion features appeared in function of time. The optimal time points for the expansion of "fit" MiHA-specific T cells were delineated using phenotypic and functional assessments including KLRG-1 and PD-1 surface markers as well as Ki67 staining and cytokine secretion assays.


RESULTS
Following a priming phase, an enrichment step and a rapid expansion stage, our method generates MiHA-specific T-cell lines. Evidence of phenotypic and functional dysfunction appear in function of culture duration, but display different characteristics following the extension of the priming or rapid expansion phases. While repeated antigen exposure during the priming phase induced the decline of the antigen-specific population and the expression of PD-1 and KLRG-1 on antigen-specific CD8+ T cells, the prolongation of an antigen-free expansion phase induced proliferation arrest and the relative loss of antigen-specific cells without impairing polyfunctional cytokine secretion or inducing PD-1 and KLRG-1 expression. A similar pattern was also observed after stimulating a virus-specific memory repertoire, except for the more rapid acquisition of exhaustion features upon repeated antigen exposure.


CONCLUSIONS
Our results offer novel insights on the impact of culture duration on the acquisition of T-cell exhaustion features. Using a new clinical-compliant protocol, we define critical parameters to monitor in order to optimally differentiate and expand MiHA-specific T cells in culture prior to adoptive transfer.
Centre de recherche de l'Hôpital Maisonneuve-Rosemont, Montreal, Quebec, Canada. vjanelle@pcitp.org.
Valérie
V
Janelle
Centre de recherche de l'Hôpital Maisonneuve-Rosemont, Montreal, Quebec, Canada. ccarli@pcitp.org.
Cédric
C
Carli
Centre de recherche de l'Hôpital Maisonneuve-Rosemont, Montreal, Quebec, Canada. jtaillefer.pftr@gmail.com.
Julie
J
Taillefer
Centre de recherche de l'Hôpital Maisonneuve-Rosemont, Montreal, Quebec, Canada. jorio@pcitp.org.
Julie
J
Orio
Centre de recherche de l'Hôpital Maisonneuve-Rosemont, Montreal, Quebec, Canada. js.delisle@umontreal.ca.|Division of Hematology-Oncology, Hôpital Maisonneuve-Rosemont and Department of Medicine, University of Montréal, Montreal, Quebec, Canada. js.delisle@umontreal.ca.
Jean-Sébastien
JS
Delisle
D019149:Bioreactors; D002460:Cell Line; D049109:Cell Proliferation; D018920:Coculture Techniques; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D016219:Immunotherapy, Adoptive; D016747:Minor Lymphocyte Stimulatory Antigens / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology
D016747:Minor Lymphocyte Stimulatory Antigens