Redirection of antileukemic reactivity of peripheral T lymphocytes using gene transfer of minor histocompatibility antigen HA-2-specific T-cell receptor complexes expressing a conserved alpha joining region

Donor-derived T lymphocytes directed against minor histocompatibility antigens (mHags) exclusively expressed on cells of the hematopoietic lineages can eliminate hematologic malignancies. Transfer of T-cell receptors (TCRs) directed against these mHags into T lymphocytes may provide a strategy to generate antileukemic T cells. To investigate the feasibility of this strategy the TCR usage of mHag HA-2-specific T-cell clones was characterized. Thirteen different types of HA-2-specific T-cell clones were detected, expressing TCRs with diversity in TCR alpha- and beta-chain usage, however, containing in the TCR alpha chain a single conserved gene segment J alpha 42, indicating that J alpha 42 is involved in HA-2-specific recognition. We transferred various HA-2 TCRs into T lymphocytes from HLA-A2-positive HA-2-negative individuals resulting in T cells with redirected cytolytic activity against HA-2-expressing target cells. Transfer of chimeric TCRs demonstrated that the HA-2 specificity is not only determined by the J alpha 42 region but also by the N-region of the alpha chain and the CDR3 region of the beta chain. Finally, when HA-2 TCRs were transferred into T cells from HLA-A2-negative donors, the HA-2 TCR-modified T cells exerted potent antileukemic reactivity without signs of anti-HLA-A2 alloreactivity. These results indicate that HA-2 TCR transfer may be used as an alternative strategy to generate HA-2-specific T cells to treat hematologic malignancies of HLA-A2-positive, HA-2-expressing patients that received transplants from HLA-A2-matched or -mismatched donors.