title: Assessment of CD4+ T cells specific for the tumor antigen SSX-1 in cancer-free individuals.
abstract: Proteins encoded by genes of the SSX family are specifically expressed in tumors and are therefore relevant targets for cancer immunotherapy. One of the first identified family members, SSX-1, is expressed in a large fraction of synovial sarcomas as a fusion protein together with the product of the SYT gene. In addition, the full-length SSX-1 antigen is frequently expressed in tumors of several other histological types such as sarcoma, melanoma, hepatocellular carcinoma, ovarian cancer and myeloma. To date, however, SSX-1 specific T cell responses have not been investigated and no SSX-1 derived T cell epitopes have been described. Here, we have assessed the presence of CD4(+) T cells directed against the SSX-1 antigen in circulating lymphocytes of cancer-free individuals. After a single in vitro stimulation with a pool of peptides spanning the entire SSX-1 protein we could detect and isolate SSX-1-specific CD4(+) T cells from 5/5 donors analyzed. SSX-1-specific polyclonal populations isolated from these cultures recognized peptides located in three distinct regions of the protein containing clusters of sequences with significant predicted binding to frequently expressed MHC class II alleles. Characterization of specific clonal CD4(+) T cell populations derived from one donor allowed the identification of several naturally processed epitopes recognized in association with HLA-DR. These data document the existence of a significant repertoire of CD4(+) T cells specific for SSX-1 derived sequences in circulating lymphocytes of any individual that can be exploited for the development of both passive and active immunotherapeutic approaches to control disease evolution in cancer patients.
authors.affiliation: Ludwig Institute Clinical Trial Center, Division of Medical Oncology, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Godefroy
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Naira E
authors.initials: NE
authors.lastname: Souleimanian
authors.forename: Luigi
authors.initials: L
authors.lastname: Scotto
authors.forename: Stefan
authors.initials: S
authors.lastname: Stevanovic
authors.forename: Yao-Tseng
authors.initials: YT
authors.lastname: Chen
authors.forename: Danila
authors.initials: D
authors.lastname: Valmori
authors.forename: Maha
authors.initials: M
authors.lastname: Ayyoub
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D017951:Antigen Presentation; D000951:Antigens, Neoplasm / Q000737:chemistry / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002461:Cell Line, Transformed / Q000276:immunology; D045744:Cell Line, Tumor / Q000276:immunology; D006682:HLA-DP Antigens / Q000276:immunology; D006683:HLA-DQ Antigens / Q000276:immunology; D006684:HLA-DR Antigens / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D008213:Lymphocyte Activation; D008545:Melanoma / Q000276:immunology / Q000473:pathology; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000737:chemistry / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology; D012016:Reference Values; D012097:Repressor Proteins / Q000737:chemistry / Q000276:immunology*; D016415:Sequence Alignment; D017385:Sequence Homology; D037182:T-Cell Antigen Receptor Specificity; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D006682:HLA-DP Antigens; D006683:HLA-DQ Antigens; D006684:HLA-DR Antigens; D009363:Neoplasm Proteins; D010446:Peptide Fragments; D012097:Repressor Proteins; C093962:synovial sarcoma X breakpoint proteins; D007371:Interferon-gamma