Dendritic cells and macrophages in the uveal tract of the normal mouse eye

Background/aims-Dendritic cells (DC) and macrophages are components of the immune cell populations in the uveal tract whose density, distribution, tur nover, and function may play a role in the maintenance of immunological hom eostasis in the eye. Little is known of these cells in the mouse eye despit e this being the predominant experimental model in many studies of ocular i mmune responses and immunoinflammatory mediated eye diseases. The aim of th e present study was to obtain further immunophenotypic data on resident tis sue macrophages and DC populations in the mouse uveal tract. Methods-Pieces of iris, ciliary body, and choroid dissected from perfusion fixed BALB/c mice were incubated whole in a variety of anti-macrophage and DC monoclonal antibodies (mAbs). Labelled cells were visualised using eithe r single or double immunoperoxidase techniques. Results-Quantitative analysis and double immunolabelling revealed that 80% of F4/80(+) cells (a mAb that recognises both DC and macrophages) in the ir is are macrophages (SER4(+)). The iris contained a network of Ia(+) cells ( 412 (SD 130) cells/mm(2)) of which two thirds appear to be DC. A similar pa ttern was observed in the ciliary body and choroid. Only a few DC in the uv eal tract were very weakly reactive for mAbs which recognise B7-1 (CD80), B 7-2 (CD86), beta 2 integrin (mAb N418), and multivesicular bodies associate d with antigen presentation (mAb M342). Conclusions-The present study reveals that the mouse uveal tract, like the rat, contains rich networks of DC and resident tissue macrophages. The netw orks of resident tissue macrophages in the mouse uveal tract closely resemb le similar networks in non-ocular tissues. The phenotype of uveal tract DC suggests they are in the "immature" phase of their life cycle, similar to L angerhans cells of the skin, thus implying their role in situ within the ey e is antigen capture and not antigen presentation.