Cathepsin E immunoreactivity in human ocular tissues: influence of aging and pathological states

We studied the antigenic expression of the aspartic proteinase cathepsin E in normal and pathologic human ocular tissues obtained from donors of different age. In the retina the enzyme was immunolocalized in neurons of outer and inner plexiform layers and in few ganglionic neurons. Muller cells were also sometimes immunoreactive for cathepsin E. An increase of neuronal enzyme immunoreactivity with age was evident. Immunocompetent blood cells invading the vitreous body were strongly immunostained for the enzyme. The enzyme is possibly involved in the retinal protein metabolism and might play immunological roles in certain pathologic events.