Background: Cultures of retinal explants have been established as a useful tool to investigate effects of pathogenic agents in vitro.
We used such cultures as a model to study the effects of choroidal melanoma on retinal organisation and function.
Methods: Rabbit retinal explants were co-cultured with human choroidal melanoma cells, or exposed to supernatants from choroidal melanoma
cell cultures, for various periods from 1 day to 10 days. The retinal explants were then studied by histology and immunocytochemistry
for glial fibrillary acidic protein (GFAP) and vimentin. The release of the pro-inflammatory interleukins IL-6 and IL-8 into
the media was measured by enzyme-linked immunosorbent assay.
Results: Both in the co-cultures and after treatment with choroidal melanoma cell supernatants for more than 1 week, the layered structure
of the retinae became disorganised. Retinal glial (Müller) cells displayed gliosis as indicated by increased GFAP immunoreactivity
and decreased immunoreactivity for vimentin. Additionally, the secretion of cytokines, particularly of IL-8, was significantly
modulated. The retinal explants produced much less IL-8 than the melanoma cells in separate cultures but increased their IL-8
release significantly after a few days’ exposure to melanoma cell-conditioned medium.
Conclusion: The results show that in cases of choroidal melanoma, the well-known morphological and inflammatory alterations of the retina
are accompanied by glial cell reactivity and up-regulated retinal cytokine secretion, and may be caused by soluble factors
secreted and induced by the melanoma.
Received: 9 May 2000 Revised: 23 August 2000 Accepted: 24 August 2000