Immunohistochemical study of epidermal growth factor receptor (EGFR) in various types of renal injury

Epidermal growth factor (EGF), a polypeptide with a potent mitogenactivity, and its receptor EGFR] have been previously identifiedin the kidney, but their expression in normal and diseased kidneyshas not been fully elucidated. In order to evaluate EGFR invarious histological types of renal injury, EGFR expressionwas studied by the immunohisto-chemical avidin–biotincomplex (ABC) method with a monoclonal antibody EGFR on paraffinsections from 10 normal kidneys, 56 renal biopsies with varioustypes of glomerulonephritis (GN), and 20 renal grafts with rejection. EGFR expression was observed in (a) 3 of 10 (30%) normal kidneys,(b) 17 of 39 (43.6%) renal biopsies with various types of GNmainly in membranous GN (57%) and in focal segmental glomerulosclerosis(FSG) (62.5%), (c) 6 of 17 (35.3%) biopsies with various typesof systemic lupus erythematosus GN, and (d) 12 of 20 (60%) renalgrafts with acute (42.9%) and chronic (69.2%) rejection. EGFRwas mainly localized to the epithelial cells of the distal andcollecting tubules and extraglomelar vessels, while it was observedless fre quently in parietal epithelial cells and along glomerularbasement membranes. Notably EGFR was detected in the epithelialcells adjacent to adhesions with Bowman's capsule and in theconnective tissue of fibrocellular crescents. In conclusion, EGFR expression was observed more frequentlyin diseased than in normal kidneys. The increased incidenceof EGFR expression in FSG, in chronic rejection, in small adhesionswith Bowman's capsule and fibrocellular crescents suggest thatEGF/EGFR may be correlated with a disturbed extra-cellular matrixproduction resulting in formation of early sclerotic lesions.