Transporter (TAP)- and proteasome-independent presentation of a melanoma-associated tyrosinase epitope.
The melanosomal protein tyrosinase is considered as a target of specific immunotherapy against melanoma. Two tyrosinase-derived peptides are presented in association with HLA-A2.1 [Wölfel et al., Eur. J. Immunol., 24, 759-764 (1994)]. Peptide 1-9 (MLLAVLYCL) is generated from the putative signal sequence. The internal peptide 369-377 is posttranslationally converted at residue 371, and its presentation is dependent on functional TAP transporters and proteasomes [Mosse et al., J. exp. Med.187, 37-48 (1998)]. Herein, we report on the processing and transport requirements for the signal sequence-derived peptide 1-9 that were studied in parallel to those for peptide 369-377. After infection of TAP-deficient (T2) and TAP-positive (T1) cells with a Modified Vaccinia Ankara construct carrying the human tyrosinase gene (MVA-hTyr), we found that recognition by CTL against peptide 1-9 did not require TAP function as opposed to recognition by CTL against peptide 369-377. When target cells with intact processing and transport functions were infected with MVA-hTyr, lysis by CTL against peptide 1-9 was not impaired by lactacystin, a specific inhibitor for the proteasome, whereas lysis by CTL against peptide 369-377 was completely abrogated. Taken together, peptide 1-9 derived from the signal sequence of tyrosinase is presented in a TAP-independent fashion and does not require proteasomes for processing. Cellular immune responses against this hydrophobic peptide can be monitored with lymphokine spot assays as documented in the case of a patient with metastatic melanoma, in whom we observed a preferential T-cell response against tyrosinase peptide 1-9 subsequent to chemoimmunotherapy. Independence of cytosolic processing and transport pathways and potentially enhanced expression levels make signal sequence-derived peptides and their carrier proteins important candidates for specific immunotherapy.
Wölfel
C
C
III. Medizinische Klinik, Johannes Gutenberg-Universität, Mainz, Germany. t.woelfel@3-med.klinik.uni-mainz.de
Drexler
I
I
Van Pel
A
A
Thres
T
T
Leister
N
N
Herr
W
W
Sutter
G
G
Huber
C
C
Wölfel
T
T
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters / Q000502:physiology*; D017951:Antigen Presentation; D003546:Cysteine Endopeptidases / Q000502:physiology*; D000939:Epitopes; D015789:HLA-A2 Antigen / Q000502:physiology; D006801:Humans; D008545:Melanoma / Q000276:immunology*; D014442:Monophenol Monooxygenase / Q000276:immunology*; D009097:Multienzyme Complexes / Q000502:physiology*; D046988:Proteasome Endopeptidase Complex; D021382:Protein Sorting Signals; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014407:Tumor Cells, Cultured
D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters; D000939:Epitopes; D015789:HLA-A2 Antigen; D009097:Multienzyme Complexes; D021382:Protein Sorting Signals; C073119:TAP1 protein, human; D014442:Monophenol Monooxygenase; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex