Detection of spontaneous CD4+ T-cell responses in melanoma patients against a tyrosinase-related protein-2-derived epitope identified in HLA-DRB1*0301 transgenic mice.
OBJECTIVE
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+ T helper (Th) cells is limited.


METHODS
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(60-74) as an HLA-DRB1*0301-restricted Th epitope. Importantly, TRP-2(60-74)-reactive human CD4+ 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+ melanoma patients. Even short-term peptide stimulation of patients' peripheral blood lymphocytes showed the presence of TRP-2(60-74)-reactive T cells, suggesting that these T cells were already activated in vivo.


CONCLUSIONS
Peptide TRP-2(60-74) might be a useful tool for the improvement of immunotherapy and immune monitoring of melanoma patients.
Paschen
Annette
A
Skin Cancer Unit of the German Cancer Research Center Heidelberg, University Hospital Mannheim, Mannheim, Germany. s.paschen@dkfz.de
Song
Mingxia
M
Osen
Wolfram
W
Nguyen
Xuan Duc
XD
Mueller-Berghaus
Jan
J
Fink
Daniela
D
Daniel
Nadine
N
Donzeau
Mariel
M
Nagel
Wolfgang
W
Kropshofer
Harald
H
Schadendorf
Dirk
D
D000818:Animals; D017951:Antigen Presentation; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D000939:Epitopes; D006684:HLA-DR Antigens / Q000276:immunology*; D059811:HLA-DRB1 Chains; D007167:Immunotherapy / Q000379:methods; D008024:Ligands; D008213:Lymphocyte Activation; D008545:Melanoma / Q000235:genetics* / Q000276:immunology*; D051379:Mice; D008822:Mice, Transgenic; D010088:Oxidoreductases / Q000276:immunology*; D012878:Skin Neoplasms / Q000235:genetics* / Q000276:immunology*
D000939:Epitopes; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; C553502:HLA-DRB1*03:01 antigen; D008024:Ligands; D010088:Oxidoreductases; C064056:tyrosinase-related protein-1