CD8(+) T lymphocytes isolated from renal cancer patients recognize tumour cells through an HLA- and TCR/CD3-independent pathway.

PURPOSE: The aim of this study was to characterize the immune response of patients affected by renal cell carcinoma (RCC). METHODS: Long-term RCC lines were established by retroviral-mediated transfer of the large T-antigen of SV40 into fresh carcinoma cells. Reactive T cell effectors were generated by iterative stimulations of patients' PBMC with autologous tumour cells. RESULTS: This protocol led to the induction of CD8(+) T cell clones reactive against the autologous tumour, but not against NK-sensitive cell lines. However, some of these effectors recognize normal renal cells, allogeneic renal carcinoma cell lines and colon and non-small cell lung carcinomas but not melanomas and lymphoblastoid lines, without evidence of shared classical HLA class I (HLA-I) molecules. Further characterization performed on the CD8(+) TCR alpha/beta(+) clone, CTL30, demonstrated that neither expression of CD1, HLA-Ia nor HLA-Ib, correlated with the T cells' recognition. Moreover, beta2m expression by target cells was not required to achieve interaction of tumour-effector cells. In agreement with this observation, the lytic activity of CTL30 was not inhibited by anti-HLA-I Ab, and antigen expression was not affected by inhibitors of antigen processing. Lytic activity of CTL30, while partially inhibited by anti-NKG2D, could not be abolished by anti-CD3 Abs. Moreover, growth and expansion of CTL30 was sustained only by T cell interaction with antigen-expressing tumour cells; unspecific mitogenic stimuli, such as anti-CD3 and PHA, did not allow T cell expansion. These results demonstrated the existence of an alpha/beta T cell population, recognizing epithelial tumour cells through an HLA-unrestricted, CD3-independent mechanism.

Rhabdomyosarcomas are potential target of MAGE-specific immunotherapies.

The search for alternative strategies of therapy remains a major issue for most neoplastic diseases. The expression of several tumor antigens makes human rhabdomyosarcomas, which are the most frequent form of soft tissue tumor in children, a good candidate for tumor-specific immunotherapy. To assess the feasibility of this approach, we evaluated the ability of rhabdomyosarcoma cell lines to process and present the MAGE-A tumor antigens to effectors of the immune system. To this end, we investigated recognition of MAGE-A-positive rhabdomyosarcoma cells by HLA-B*3701-restricted T cells specific for a MAGE-A-derived peptide. Low level of HLA expression impaired recognition of the tumor cells. Therefore, to obtain HLA expression avoiding the use of IFN-gamma and TNF-alpha, which could affect the proteasome activity, a rhabdomyosarcoma line was transduced by a retroviral vector encoding the HLA-B*3701 allele. Recognition of the infected cells was then observed also in the absence of IFN-gamma and TNF-alpha treatment, thus demonstrating that rhabdomyosarcoma cells were indeed able to naturally process and present the MAGE-A antigens. These results demonstrate that rhabdomyosarcoma cells expressing MAGE-A can be targets of tumor-specific effectors, suggesting the feasibility of clinical protocols of specific immunotherapy also for the treatment of rhabdomyosarcoma.