Recognition of Melanoma-Associated Peptides by Peripheral Blood Mononuclear Cells of Ocular Melanoma Patients

Abstract

Melanoma of the eye is the most common intraocular malignancy in adults with approximately 50% of patients subsequently developing metastases, usually of the liver. In the United Kingdom there are 300–400 new cases of ocular/uveal melanoma each year. Tumour-associated antigens have been described for ocular melanoma and there is evidence to suggest that choroidal melanoma cells can elicit an immune response to tumour antigens [1]. It has already been shown that although uveal melanoma cells do not express the MAGE genes, they do express high levels of the melanocyte lineage specific genes, tyrosinase, gp100 and melan-A/MART-1 [2] (Table 1). Three nonamer melanoma-associated peptides, restricted by HLA-A0201, were selected from the genes tyrosinase, gp100 and melan-A/MART-1, for the study, and coded, T9₃₆₈, G9₂₈₀ and M9₂₇ respectively [4-6] (Table 2). These peptides were considered most suitable for the study since, HLA-A0201 is the most frequently expressed Class I allele (49% of Caucasians), and they have been shown to have both the ability to bind to HLA-A0201, and are capable of eliciting a CTL response, restricted by this haplotype, in cutaneous melanoma (Table 2).

Table 1. Expression of melanoma antigen genes in primary uveal melanomas [2]