title: Melanomas that develop within the eye inhibit lymphocyte proliferation.
abstract: Experiments were performed to compare the ability of ocular and skin melanoma cells to stimulate T cells. Primary melanoma cell lines were obtained from a series of patients with either eye or skin melanoma. The ability of tumor cells to stimulate T cells in the absence of exogenous growth factors was assessed in mixed-lymphocyte tumor cell cultures in which allogeneic lymphocytes were stimulated with irradiated ocular or skin melanoma cells. Expression of HLA class I and class II on tumor cells, in the presence or absence of IFN-gamma, was determined by flow cytometry. The ability of tumor cells to inhibit T-cell proliferation was determined by adding various concentrations of irradiated tumor cells to standard mixed-lymphocyte cultures. Our results indicate that primary skin melanoma cells induce vigorous proliferation of allo-antigen-specific T cells. By contrast, ocular melanoma cells failed to induce significant T-cell proliferation. The failure of ocular melanoma cells to stimulate lymphocyte proliferation was not due to low levels of either class I or class II on tumor cells since tumor cells treated with IFN-gamma expressed high levels of class I and class II but still failed to induce lymphocyte proliferation. Ocular melanoma cells inhibited lymphocyte proliferation, as shown by experiments in which a small number of tumor cells prevented proliferation of T cells in mixed-lymphocyte cultures. Inhibition of lymphocyte proliferation required cell-to-cell contact, and supernatants from tumor cell cultures did not prevent lymphocyte proliferation. Moreover, the ability of ocular melanoma cells to inhibit T-cell proliferation was lost when tumor cells migrated from the eye and formed hepatic metastases. We conclude that there is a fundamental difference in the immunogenicity of ocular and skin melanoma cells. Ocular melanomas, but not primary skin melanomas, are poorly immunogenic tumors that inhibit T-cell proliferation. Our results imply that the immunogenicity of melanoma cells is altered when they develop within the unique ocular micro-environment.
authors.affiliation: The Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA. verbik@vision.eri.harvard.edu
authors.forename: D J
authors.initials: DJ
authors.lastname: Verbik
authors.forename: T G
authors.initials: TG
authors.lastname: Murray
authors.forename: J M
authors.initials: JM
authors.lastname: Tran
authors.forename: B R
authors.initials: BR
authors.lastname: Ksander
mesh_terms: D000951:Antigens, Neoplasm / Q000032:analysis; D002455:Cell Division / Q000187:drug effects; D005134:Eye Neoplasms / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000032:analysis; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D006801:Humans; D007111:Immunity, Cellular; D007371:Interferon-gamma / Q000494:pharmacology; D008545:Melanoma / Q000276:immunology* / Q000556:secondary; D009928:Organ Specificity / Q000276:immunology; D012878:Skin Neoplasms / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology*; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D000951:Antigens, Neoplasm; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D007371:Interferon-gamma