Detection of Spontaneous CD4 super(+) T-Cell Responses in Melanoma Patients against a Tyrosinase-Related Protein-2-Derived Epitope Identified in HLA-DRB10301 Transgenic Mice

• Published in: Clinical cancer research Vol. 11; no. 14; pp. 5241 - 5247
• Main Authors: Paschen, Annette, Song, Mingxia, Osen, Wolfram, Nguyen, Xuan Duc, Mueller-Berghaus, Jan, Fink, Daniela, Daniel, Nadine, Donzeau, Mariel, Nagel, Wolfgang, Kropshofer, Harald, Schadendorf, Dirk
• Format: Journal Article
• Language: English
• Published: 01-07-2005
• ISSN: 1078-0432

PURPOSE: The frequently expressed differentiation antigen tyrosinase-related protein-2 (TRP-2) has repeatedly been described as a target of spontaneous cytotoxic T-cell responses in melanoma patients, suggesting that it might be an ideal candidate antigen for T cell-based immunotherapy. As a prerequisite for immunization, T-cell epitopes have to be identified. Whereas a number of HLA class I-presented TRP-2-derived epitopes are known, information about HLA class II-presented antigenic ligands recognized by CD4 super(+) T helper (Th) cells is limited. Experimental Design: The search for TRP-2-derived Th epitopes was carried out by competitive in vitro peptide binding studies with predicted HLA-DRB1*0301 ligands in combination with peptide and protein immunizations of HLA-DRB1*0301 transgenic mice. In vivo selected candidate epitopes were subsequently verified for their immunogenicity in human T-cell cultures. RESULTS: This strategy led to the characterization of TRP-2 sub(60-74) as an HLA-DRB1*0301-restricted Th epitope. Importantly, TRP-2 sub(60-74)-reactive human CD4 super(+) Th cell lines, specifically recognizing target cells loaded with recombinant TRP-2 protein, could be established by repeated peptide stimulation of peripheral blood lymphocytes from several HLA-DRB1*03 super(+) melanoma patients. Even short-term peptide stimulation of patients' peripheral blood lymphocytes showed the presence of TRP-2 sub(60-74)-reactive T cells, suggesting that these T cells were already activated in vivo. CONCLUSION: Peptide TRP-2 sub(60-74) might be a useful tool for the improvement of immunotherapy and immune monitoring of melanoma patients.