IMMUNOHISTOCHEMICAL CHARACTERIZATION OF RETINAL GLIAL-CELL CHANGES INAREAS OF VASCULAR OCCLUSION SECONDARY TO DIABETIC-RETINOPATHY

Purpose: To study changes in retinal glial cell components in areas of vascular occlusion secondary to diabetic retinopathy. Material: The r etina from ten eyes of six diabetic patients and from five eyes of fiv e normal controls were studied for immunoreactivity to glial fibrillar y acid protein and vimentin (glial cells), S-100 protein (perivascular glial cells), carbonic anhydrase isoenzyme II and CD-57 antigen (Mull er cells), and CD-68 antigen (microglia). Results: The study showed in creased immunoreactivity to S-100 protein, corresponding to perivascul arly located glial cells in the retina from diabetic patients, except for areas of vascular occlusion where this immunoreactivity was absent . Furthermore, the material invading the lumen of former retinal vesse ls in areas of vascular occlusion showed immunoreactivity to CAH-II an d CD-57, suggesting that this material represents ingrowth of retinal Muller cells. Conclusions: The findings suggest that at least two type s of changes in retinal glial cells are involved in the pathophysiolog y of diabetic retinopathy, i.e. 1) Reactive changes in the perivascula r glial cells in the retina, and 2) Muller cell ingrowth into the form er lumen of occluded retinal vessels.