IMMUNOHISTOCHEMICAL FINDINGS IN EYES OF CATS SEROLOGICALLY POSITIVE FOR FELINE IMMUNODEFICIENCY VIRUS (FIV)

In this study the eyes of 15 cats in the terminal stage of FIV infecti on were examined. The findings were compared to those in cats, which w ere euthanized because of other infectious diseases or for non-infecti ous reasons. Thirteen FIV-infected cats showed an anterior uveitis by means of light microscopy. No accumulation of retinal lesions were fou nd in FIV-infected cats compared to the other cats examined. Additiona lly, there were no indications of lesions caused by opportunistic infe ctions. In the posterior segments of the eyes, immunohistochemical exa minations proved the plasma proteins C3 and IgG to be predominantly in travascular. The eyes of 11 serologically FIV-positive cats were avail able for immunohistochemical examination. In all 11 cats at least one of the plasma proteins C3 or IgG could be detected in the extravascula r tissue of the anterior uvea. The extravascular presence of plasma pr oteins within the tissue seemed to be caused by an increased permeabil ity of the vessels due to inflammation. Furthermore, the similar extra vascular distribution pattern of IgG and complement component C3 in fo ur cases indicated that immune complexes may play a role in the anteri or uveitis of FIV-infected cats.