In vitro-generated MART-1-specific CD8 T cells display a broader T-cell receptor repertoire than exvivo naïve and tumor-infiltrating lymphocytes.

Abstract

The differentiation of human hematopoietic stem cells into CD8 T cells can be achieved invitro with the OP9-DL4 system. We considered that in the absence of medullary thymic epithelial cells, which serve to restrict the breath of the T-cell receptor (TCR) repertoire by expressing tissue-restricted antigens, a distinct repertoire would be generated invitro. To test this notion, we compared the TCR-Vα/Vβ (TRAV/TRBV) gene usage of major histocompatibility complex-restricted antigen (MART-1)-specific T cells generated invitro to that from exvivo naïve T cells and tumor-infiltrating lymphocytes (TILs) using high-throughput DNA sequencing. In contrast to naïve T cells and TILs, which showed the expected narrow TRAV repertoire, invitro-generated MART-1-specific T cells used almost all TRAV gene families and displayed unique CDR3 lengths. Our work demonstrates that the OP9-DL4 system supports the creation of a broad antigen-specific TCR repertoire, suggesting that T cells generated invitro may undergo a different set of selection events that otherwise constrains the TCR repertoire of thymus-derived T cells.