Influence of interleukin 10 and transforming growth factor-beta on T cell stimulation through allogeneic retinal pigment epithelium cells in vitro

The effect of interleukin 10 (IL-10) and transforming growth factor-beta (TGF-beta) on the immunological capability of human retinal pigment epithelium (RPE) cells was tested by measuring the proliferation of allogeneic T cells after stimulation through the RPE cells in vitro. For this, human RPE cells were activated with different concentrations of interferon-gamma (0, 50, 100 and 250 U/ml) used as stimulator cells. The following T cell proliferation was measured with a tetrazolium-based colorimetric assay over a period of up to 4 days. Our results show that RPE cells are able to stimulate allogeneic T cells in the presence or absence of professional antigen-presenting cells (macrophages). Additionally, the proliferation could be significantly decreased by IL-10 or TGF-beta. The maximum of suppression, especially by TGF-beta, was found after 48 and 72 h of incubation. This shows that the antigen-presenting properties of human RPE cells can be altered in culture.