Identification of cellular immune responses to NET-1/C4.8, a progression associated marker in cervical carcinoma

NET-1/C4.8 is a cellular protein belonging to the tetraspanin family of membrane proteins. Expression of this protein is strongly upregulated throughout the epithelial layer in a subset high grade cervical neoplasia and in most of the undifferentiated squamous cell cancers. Due to this expression pattern, C4.8 could be regarded as a tumor associated antigen. We have analyzed the putative immunogenicity of C4.8 for T cells. Five HLA-A2 restricted peptide epitopes were identified by prediction algorithms (BIMAS, SYFPEITHI) and synthetic peptides with high binding score were tested for their immunogenicity. Two of 6 T cell lines of healthy HLA-A2 positive donors primed in vitro by cervical cancer cell lines responded with interferon-gamma secretion to stimulation with two of the peptides. In tumor-infiltrating lymphocyte lines established from 2 cervical cancer patients reactivity with the C4.8 peptides could be detected by interferon-gamma ELISpot. This finding proofed relevance of the antigen and the identified peptide epitopes. Therefore, C4.8 may be further evaluated as a tumor antigen useful for immunotherapy and immunomonitoring of cervical cancer patients.