The intronic region of an incompletely spliced gp100 gene transcript encodes an epitope recognized by melanoma-reactive tumor-infiltrating lymphocytes.

PF Robbins, M El-Gamil, YF Li… - … (Baltimore, Md.: 1950 …, 1997 - journals.aai.org
PF Robbins, M El-Gamil, YF Li, EB Fitzgerald, Y Kawakami, SA Rosenberg
Journal of immunology (Baltimore, Md.: 1950), 1997journals.aai.org
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 …
Abstract
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.
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