A parathyroid-hormone-related-protein (PTH-rP)-specific cytotoxic T cell response induced by in vitro stimulation of tumour-infiltrating lymphocytes derived from prostate camcer metastates, with epitope peptide-loaded autologous dendritic cells and low-dose IL-2.

摘要

Bone metastases are one of the most common events in patients with prostate carcinoma. PTH-rP, a protein produced by prostate\udcarcinoma and other epithelial cancers, is a key agent for the development of bone metastases. A PTH-rP-derived peptide, designated PTR-\ud4 was identified, which is capable to bind HLA-A2.1 molecules and to generate PTH-rP-specific cytotoxic T cell (CTL) lines from healthy HLAA2.1+\udindividual peripheral-blood-mononuclear-cells (PBMC). In this model, we investigated the in vitro possibility of generating an efficient\udPTH-rP specific CTL response by cyclical stimulations with IL-2 and PTR-4 peptide-pulsed autologous dendritic cells (DC), of HLA-A2.1+\udtumour infiltrating lymphocytes (TIL) derived from a patient with metastatic prostate carcinoma. A T cell line generated in this way (called TMPTR-\ud4) had a CD3+, CD5+, CD4–, CD8+, CD45Ro+, CD56– immunophenotype and a HLA-A2.1 restricted cytotoxic activity to PTR-4-peptide\udpulsed CIR-A2 (HLA-A2.1+) target cells, PTH-rP+/HLA-A2.1+ CIR-A2 transfected with PTH-rP gene, prostate carcinoma LNCaP cells, and\udautologous metastatic prostate cancer cells (M-CaP). These lymphocytes were not cytotoxic to HLA-A2.1+ targets not producing PTH-rP, such\udas peptide-unpulsed CIR-A2 and colon carcinoma SW-1463, cell lines. Our results provide evidence that PTR-4 peptide-pulsed autologous\udDC may break the tolerance of human TIL against the autologous tumour by inducing a PTH-rP-specific CTL immune reaction. In conclusion\udPTR-4 peptide-pulsed autologous DC may be a promising approach for vaccine-therapy and antigen-specific CTL adoptive immunotherapy\udof hormone-resistant prostrate cancer.