In the post-genomic era, the identification of tumor-associated antigens that elicit a humoral response is allowed at the protein level using proteomics. Indeed, the screening of autoantibodies using 2-D Western blot experiments with sera from cancer patients, followed by the subsequent identification of the target protein by mass spectrometry and database search has permitted the exploitation of the B-cell repertoire of patients with cancer. Applied to several types of cancer, a proteomic-based approach has revealed a high frequency of autoantibodies in sera from patients. Several of the antigenic proteins identified may constitute novel cancer markers and may have clinical utility in diagnosis or in establishing prognosis. Furthermore, the approach has allowed to distinguish isoforms that may help to define epitopes. On the other hand, the analysis of the expression levels of some of the antigenic proteins has revealed differential expression in tumors as compared with healthy tissues that might explain antigenicity.

Key words: Tumor antigens, autoantibodies, 2-D Western blot, mass spectrometry, proteomics.