Immunohistochemical investigation of the distribution of immunoglobulins G, A and M within the anterior uvea of the normal equine eye.

Distribution of the immunoglobulin (Ig) classes G, A and M within the anterior uvea of eight clinically normal equine eyes was examined using indirect immunoperoxidase labelling. Increased staining intensity of stromal IgG and IgA was observed within the ciliary processes, the iris stroma being relatively free of immunoglobulin. This may reflect anatomical variation in the permeability of the uveal microvasculature to lipid insoluble plasma macro-molecules. Intracellular IgG and IgA were observed within the non-pigmented ciliary epithelium in seven and four of the eight eyes respectively, although wide variation between numbers of Ig bearing cells in each eye was noted. It was suggested that these cells may have a role in the removal of Ig from the posterior chamber aqueous. Plasma cells, of IgG isotype, were observed in only one eye, suggesting that intraocular production of Ig is not a feature of the normal equine eye.