Allo-Major Histocompatibility Complex–Restricted Cytotoxic T Lymphocytes Engraft in Bone Marrow Transplant Recipients Without Causing Graft-Versus-Host Disease

Cyclin D1-specific cytotoxic T lymphocytes are present in the repertoire of cancer patients: implications for cancer immunotherapy

PURPOSE

Cyclin D1, a key cell cycle regulator, is overexpressed in multiple types of cancer. Such tumor-associated genes may be useful targets for cancer immunotherapy. Nevertheless, it had previously been suggested that efficient T cells recognizing cyclin D1-derived epitopes are absent from the repertoire because of thymic deletion. We attempted to induce autologous CTL from healthy donors and patients with cyclin D1-overexpressing tumors using a highly efficient T-cell expansion system based on CD40-activated B cells as antigen-presenting cells.

EXPERIMENTAL DESIGN

Cyclin D1-derived, HLA-A*0201-restricted epitopes were predicted by multiple computer algorithms, screened in HLA-A2-binding assays, and used for T-cell stimulation. The generated CTL lines and clones were analyzed by IFN-gamma enzyme-linked immunosorbent spot assay or cytolysis assay.

RESULTS

After screening, at least two naturally processed and presented HLA-A*0201-binding cyclin D1 epitopes were identified. CTL specific for these epitopes could be successfully generated from HLA-A2(+) donors. T cells efficiently recognized target cells pulsed with the cognate peptide and cyclin D1-expressing tumor cell lines in an HLA-A*0201-restricted manner. More importantly, HLA-A*0201-matched, primary cyclin D1(+) tumor cells were efficiently recognized by cyclin D1-specific CTL. These CTL could be generated from patients with mantle cell lymphoma and cyclin D1(+) colon cancer.

CONCLUSIONS

These results underscore that cyclin D1 needs to be considered as a target for broad-based antitumor immunotherapy.

The peptide-specific alloreactive human T cell repertoire varies largely between individuals and is not extended in HLA-A*0205--anti-HLA-A*0201 pairings

Alloreactive T cells recognize framework or peptide-dependent determinants on foreign MHC molecules. Among the peptide-dependent alloreactive T cells a significant proportion is specific for one particular peptide presented by the allo-MHC molecule as antigen-specific T cells would do. Such alloreactive, peptide-specific T cells are referred to as 'allorestricted'. High-avidity HLA-A*02 allorestricted cytotoxic T lymphocyte (CTL) clones specific for peptide libraries can be generated from HLA-A*02(-) donors. We made use of this technique to study the role of closely related self-HLA molecules on shaping of the alloreactive T cell repertoire. Peripheral blood lymphocytes from HLA-A*0205 individuals were stimulated by HLA-A*0201 targets pulsed with an HLA-A*0201 peptide library. We did not observe a bias towards peptide-specific CTL in the HLA-A*0201-directed alloreactive repertoire of HLA-A*0205 donors as compared to HLA-A*02(-) donors. Comparison of the alloreactive T cell response between two donors having similar HLA haplotypes demonstrated that the allorestricted T cell repertoire is largely different between individuals.