Expression of Fas and Fas ligand in uveal melanoma: biological implicationand prognostic value

The interaction between Fas and Fas ligand is one possible immune escape me chanism used by tumour cells. In the present study, melanoma tissue from 10 3 patients who underwent enucleation for malignant uveal melanoma (iris mel anomas excluded) was stained by immunohistochemistry with monoclonal antibo dies specific for Fas, Fas ligand, CD3, CD8, and CD68. Histological and cli nical data for these tumours were assessed. Both Fas and Fas ligand were de tected in uveal melanomas. Cells of the monocyte/macrophage lineage rather than T-cells were the predominant group of tumour-infiltrating cells. The m etastasis-free 5-year survival rates in the univariate analyses were consid erably lower in patients with tumours that lacked Fas ligand expression ( < 35% of the tumour cells), in the presence of more than 50 CD8-positive cel ls in 20 high-power fields and in the presence of more than 100 CD3-positiv e cells in 20 high-power fields. Fas and Fas ligand expression was associat ed with scleral infiltration. After adjustment for scleral infiltration, th e predictive value of both Fas and Fas ligand expression was markedly decre ased. In addition, the CD3- and C138-positive cell count was positively ass ociated with the histological cell type. Cox proportional hazards models sh owed that the presence of CD3- and CD8-positive cells was not an independen t prognostic factor after adjusting for histological cell type. This prelim inary observation deserves further investigation, which may shed more light on the immune escape mechanisms of this tumour and thus enable novel thera peutic strategies. The clinical relevance of this observation is limited, a s more predictive parameters have been described for uveal melanoma. Copyri ght (C) 2001 John Wiley & Sons, Ltd.