The intronic region of an incompletely spliced gp100 gene transcript encodes an epitope recognized by melanoma-reactive tumor-infiltrating lymphocytes.
Recent studies have characterized a number of the Ags that are recognized by melanoma-reactive T cells. Although the majority of tumor Ags appear to represent nonmutated gene products, a variety of epitopes have been shown to arise from either mutated or alternatively processed transcripts. Here, we report that the screening of a cDNA library with a HLA-A24-restricted melanoma-reactive T cell cloid derived from tumor infiltrating lymphocytes resulted in the isolation of a variant of the gp100 gene that had retained the entire fourth intron of this gene, termed gp100-in4. The gp100-in4 transcript could be detected by reverse transcriptase-PCR but could not be detected in Northern blots conducted with melanoma RNA, indicating that it represents a relatively rare transcript. Read-through of this transcript into the region corresponding to the fourth intron gave rise to an additional 35 amino acids not found in the normal gp100 glycoprotein, and a peptide within this region conforming to the HLA-A24 consensus motif (VYFFLPDHL) was shown to be recognized by the T cell cloid. The sequence of the intron was identical with that of a previously isolated genomic gp100 clone, and T cells that recognized the gp100-in4 gene product were found to recognize HLA-A24-matched allogeneic melanoma cell lines and melanocytes, demonstrating that this represents a nonmutated epitope. These results further extend the types of Ags that can be recognized by melanoma-reactive T cells to aberrant transcripts of melanosomal genes.
Robbins
P F
PF
Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
El-Gamil
M
M
Li
Y F
YF
Fitzgerald
E B
EB
Kawakami
Y
Y
Rosenberg
S A
SA
D000595:Amino Acid Sequence; D000951:Antigens, Neoplasm / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D000939:Epitopes / Q000276:immunology*; D015234:HLA-A Antigens / Q000276:immunology; D059871:HLA-A24 Antigen; D006801:Humans; D007438:Introns / Q000235:genetics / Q000276:immunology; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology*; D008545:Melanoma / Q000276:immunology* / Q000473:pathology; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics / Q000276:immunology*; D012326:RNA Splicing; D014407:Tumor Cells, Cultured; D058951:gp100 Melanoma Antigen
D000951:Antigens, Neoplasm; D000939:Epitopes; D015234:HLA-A Antigens; D059871:HLA-A24 Antigen; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; C548637:PMEL protein, human; D058951:gp100 Melanoma Antigen