Purpose. The vascular choroid layer of the eye contains a rich network of antigen presenting cells (dendritic cells and resident macrophages). //; vitro studies of enriched choroidal dendritic cells have shown that they present antigen to naive T cells. The purpose of this investigation was to study the effect of the ocular choroidal micro-environment on the function of choroidal APCs. Methods. Fresh and cultured, rat and human, choroidal APCs were isolated by both positive and negative selection techniques, and antigen presenting function assayed by MLR und soluble antigen stimulation. Cytokine mRNA expression and protein release from cultured retinal pigment epithelial (RPE) cells were quantified under diflerent culture conditions, including co-culture with APC's. Results. APC function of choroidal dendritic ceils was considerably enhanced by resident macrophages although resident macrophages themselves were poor APCs. Since choroidal dendritic cells are normally intimately associated with RPE cells at ihe blood retinal barrier, resident macrophage and dendritic cell activity in ihe choroid may be altered by cytokines such as GM-CSF. RANTES, MCP and M1P- la and b. Our data shows thai RANTES release by RPE cells was upreguiated by IL-1 and TNFa. but down regulated by IL-4. In contrast. GMCSF release was increased in response to IL-1 and TNFa. but decreased by IFNg. In addition the function of choroidal dendritic cells was shown to be modulated by cytokines which were differentially released by RPE cells. Conclusions. These results demonstrate the importance of the microenvironment in regulating APC function and immune response in the eye and have implications for immune responses in tissues generally.
|Journal||Investigative Ophthalmology and Visual Science|
|Publication status||Published - 1 Dec 1997|