Distribution of tissue plasminogen activator in human and monkey eyes. An immunohistochemical study

The authors examined various structures of human and rhesus monkey eyes for the presence of tissue plasminogen activator (t-PA) by using the peroxidase-antiperoxidase immunohistochemical technique with a monoclonal antibody specific for human t-PA. Positive staining for t-PA was observed both intracellularly and in the extracellular matrix of many tissues in both species. The tissues which stained intensely for t-PA included the corneal endothelium, corneal epithelium, trabecular meshwork, lens epithelium, peripheral vitreous, uveal tract, inner retina, and all vascular endothelia. The apparent minor difference in staining intensity between human and monkey eyes may be related to the time-dependent degradation of t-PA, to variations in the tissue content of t-PA, or to the difference in animal species. The discussion includes a consideration of the fibrinolytic activity of t-PA and of its emerging role in the destructive remodeling of the extracellular matrix in various ocular structures.