| Autor: |
Meidenbauer N; Department of Hematology/Oncology, University of Regensburg, Regensburg, Germany., Zippelius A, Pittet MJ, Laumer M, Vogl S, Heymann J, Rehli M, Seliger B, Schwarz S, Le Gal FA, Dietrich PY, Andreesen R, Romero P, Mackensen A |
| Jazyk: |
angličtina |
| Zdroj: |
Cancer research [Cancer Res] 2004 Sep 01; Vol. 64 (17), pp. 6319-26. |
| DOI: |
10.1158/0008-5472.CAN-04-1341 |
| Abstrakt: |
Tumor-reactive T cells play an important role in cancer immunosurveillance. Applying the multimer technology, we report here an unexpected high frequency of Melan-A-specific CTLs in a melanoma patient with progressive lymph node metastases, consisting of 18 and 12.8% of total peripheral blood and tumor-infiltrating CD8+ T cells, respectively. Melan-A-specific CTLs revealed a high cytolytic activity against allogeneic Melan-A-expressing target cells but failed to kill the autologous tumor cells. Loading of the tumor cells with Melan-A peptide reversed the resistance to killing, suggesting impaired function of the MHC class I antigen processing and presentation pathway. Mutations of the coding region of the HLA-A2 binding Melan-A26-35 peptide or down-regulation of the MHC class I heavy chain, the antigenic peptide TAP, and tapasin could be excluded. However, PCR and immunohistochemical analysis revealed a deficiency of the immunoproteasomes low molecular weight protein 2 and low molecular weight protein 7 in the primary tumor cells, which affects the quantity and quality of generated T-cell epitopes and might explain the resistance to killing. This is supported by our data, demonstrating that the resistance to killing can be partially reversed by pre-exposure of the tumor cells to IFN-gamma, which is known to induce the immunoproteasomes. Overall, this is the first report of an extremely high frequency of tumor-specific CTLs that exhibit competent T-cell-effector functions but fail to lyse the autologous tumor cells. Immunotherapeutic approaches should not only focus on the induction of a robust antitumor immune response, but should also have to target tumor immune escape mechanisms. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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