Cloning of a new gene encoding an antigen recognized by melanoma-specific HLA-A24-restricted tumor-infiltrating lymphocytes

Abstract

The role of tumor-specific T cells in mediating the regression of metastatic melanoma has been suggested by the clinical response of patients to treatment with tumor-infiltrating lymphocytes (TIL). A number of Ags recognized by class I-restricted melanoma-specific T cells have recently been isolated, raising the hope that this will lead to the development of improved therapies. In this study, we report the cloning of a tumor Ag recognized by T cells from melanoma patient 888. Previously, we reported that TIL 888, grown from the tumor of this patient, recognized tyrosinase in an HLA-A24-restricted fashion. This line, when infused into the autologous patient, resulted in complete regression of multiple metastases. Three years later, a second TIL line, TIL 1290, was isolated from a recurrent pelvic tumor. Infusion of a mixture of TIL 888 and TIL 1290 cell lines into the patient resulted in complete regression of a residual abdominal mass and the patient remains disease-free 2 yr later. The TIL 1290 cell line, which recognized melanoma in an HLA-A24-restricted manner, failed to recognize tyrosinase. TIL 1290 was then used to screen an 888 melanoma cDNA library, and an Ag was isolated that did not correspond to any found in sequence databases. This gene, termed p15, was found to be expressed in a variety of normal tissues, and a peptide epitope recognized by TIL 1290 was found to represent the product of an nonmutated gene. Screening of additional cDNA pools resulted in the isolation of a second clone which stimulated TIL 1290. This clone also appeared to represent a transcript of the p15 gene, indicating that this gene may encode the predominant Ag recognized by TIL 1290.