IMMUNOREACTIVITY AGAINST TAU, AMYLOID PRECURSOR PROTEIN, AND BETA-AMYLOID IN THE HUMAN RETINA

Purpose, Increased immunoreactivity (IR) of beta-amyloid and the amylo id-associated proteins tau and amyloid precursor protein (APP) in the brain have been linked to the pathogenesis of neurodegenerative disord ers such as Alzheimer's disease. However, the expression of these prot eins has not been investigated in the normal or diseased human retina. Methods. Using immunohistochemical techniques, we examined the distri bution and age-related changes of anti-tau-l, anti-tau-2, anti-APP, an d anti-beta-amyloid IR in the human retina at Various ages (n = 24), i n retinitis pigmentosa (RP, n = 6), and in age-related macular degener ation (ARMD, n = 10). Results. Tau-l immunoreactivity was intense in t he inner retinal layers and did not change with age or in RP. Eyes wit h ARMD showed less intense staining but exhibited a similar distributi on. Tau-2 IR was faint and did not change with age but was mildly incr eased in the retinal pigment epithelium (RPE) of eyes with RP and in t he retina of eyes with ARMD. APP IR was most prominent in the ganglion cell and nerve fiber layer, and it appeared to increase in ganglion c ells of older persons and in RPE cells of eyes with RP and ARMD. Beta- amyloid IR was only detected focally in sub-RPE deposits in eyes from older persons. Conclusions. The proteins investigated in this study ar e present in the human retina. The staining pattern of tau is differen t from the brain, but it shows no age-related changes. The increased i mmunoreactivity of APP in retinal ganglion cells of older eyes and in RPE cells of eyes with RP and ARMD, as well as the patchy staining of beta-amyloid within sub-RPE deposits, might indicate a relationship of these proteins to retinal aging and possibly to retinal degeneration in RP.