L-Arginine supplementation improves the survival of virus-specific CD8+ T cells during in vitro expansion.

INTRODUCTION

Virus-specific T cell therapy is a promising treatment for life-threatening viral infections following allogeneic hematopoietic stem cell transplantation. However, its efficacy is limited by apoptotic cell loss during in vitro expansion and the cryopreservation process.

MATERIALS AND

METHODS

Human virus-specific T cells were expanded in vitro with interleukin-7 and interleukin-15 in RPMI 1640-based medium with or without L-arginine supplementation, and their survival, phenotype, mitochondrial function, and cytokine signaling were evaluated.

RESULTS

Supplementation of the culture medium with L-arginine enhanced the survival of human virus-specific T cells during in vitro expansion. Supplementation of the RPMI 1640-based culture medium with L-arginine reduced apoptosis and was accompanied by increased expression of the anti-apoptotic protein MCL-1 in virus-specific CD8+ T cells. In parallel, modest differences in exhaustion- and differentiation-associated markers were observed. Consistent with these survival-associated changes, preservation of mitochondrial membrane potential was concurrently observed in non-apoptotic CD8+ T cells. Among several culture-associated factors that may contribute to mitochondrial preservation, L-arginine availability was associated, at least in part, with common gamma-chain cytokine-induced phosphorylation of mammalian target of rapamycin signalling and signal transducer and activator of transcription 5 downstream of interleukin-7 and interleukin-15 during in vitro culture.

CONCLUSION

Together, these findings support L-arginine supplementation as a simple and clinically applicable strategy to enhance the durability of virus-specific T cell products during in vitro expansion, as well as cryopreservation and thawing.