Mammalian eyes and associated tissues contain molecules that are immunologically related to cartilage proteoglycan and link protein.

Monospecific antibodies to bovine nasal cartilage proteoglycan monomer and link protein were used to demonstrate that immunologically related molecules are present in the bovine eye and associated tissues. With immunofluorescence microscopy, reactions for both proteoglycan and link protein were observed in the sclera, the anterior uveal tract, and the endoneurium of the optic nerve of the central nervous system. Antibody to bovine nasal cartilage proteoglycan also reacted with some connective tissue sheaths of rectus muscle and the perineurium of the optic nerve of the central nervous system. Antibody to proteoglycan purified from rat brain cross-reacted with bovine nasal cartilage proteoglycan, indicating structural similarities between these proteoglycans. ELISA studies and crossed immunoelectrophoresis demonstrated that purified dermatan sulphate proteoglycans isolated from bovine sclera did not react with these antibodies but that the antibody to cartilage proteoglycan reacted with other molecules extracted from sclera. Two molecular species resembling bovine nasal link protein in size and reactivity with antibody were also demonstrated in scleral extracts: the larger molecule was more common. Antibody to link protein reacted with the media of arterial vessels demonstrating the localization of arterial link protein described earlier. Tissues that were unstained for either molecule included the connective tissue stroma of the iris, retina, vitreous body, cornea, and the remainder of the uveal tract. These observations clearly demonstrate that tissues other than cartilage contain molecules that are immunologically related to cartilage-derived proteoglycans and link proteins.