[Identification of cancer antigens of relevance for specific cancer immunotherapy]

Cytolytic T lymphocytes (CTL) play a major role in the recognition and destruction of tumor cells by the immune system. In the last ten years, our team has identified at the molecular level a number of markers, called antigens, whose presence at the surface of tumor cells allow CTL to recognize such cells. Some of these antigens, including those encoded by the MAGE genes, are absent on all normal cells, and therefore constitute ideal targets for cancer vaccines aimed at increasing the activity of anti-tumor lymphocytes. Such vaccines are currently tested in clinical trials with melanoma patients. These antigens consist of small peptides that are presented by HLA molecules and that result from the degradation of intracellular proteins. This degradation is performed by an intracellular proteolytic complex called the proteasome. We recently observed that dendritic cells, which in the lymph node are responsible for antigen presentation to the lymphocytes in order to initiate the immune response, are inefficient to produce some peptides because they contain a different proteasome called "immunoproteasome". This unexpected observation may have important implications for the choice of vaccination strategies.