IMMUNOHISTOCHEMICAL STUDY OF EPIDERMAL-GROWTH-FACTOR RECEPTOR (EGFR) IN VARIOUS TYPES OF RENAL INJURY

Epidermal growth factor (EGF), a polypeptide with a potent mitogen act ivity, and its receptor [EGFR] have been previously identified in the kidney, but their expression in normal and diseased kidneys has not be en fully elucidated. In order to evaluate EGFR in various histological types of renal injury, EGFR expression was studied by the immunohisto chemical avidin-biotin complex (ABC) method with a monoclonal antibody EGFR1 on paraffin sections from 10 normal kidneys, 56 renal biopsies with various types of glomerulonephritis (GN), and 20 renal grafts wit h 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 GN mainly in membranous GN (57%) and in focal segmental glomerulosclerosi s (FSG) (62.5%), (c) 6 of 17 (35.3%) biopsies with various types of sy stemic lupus erythematosus GN, and (d) 12 of 20 (60%) renal grafts wit h acute (42.9%) and chronic (69.2%) rejection. EGFR was mainly localiz ed to the epithelial cells of the distal and collecting tubules and ex traglomelar vessels, while it was observed less frequently in parietal epithelial cells and along glomerular basement membranes. Notably EGF R was detected in the epithelial cells adjacent to adhesions with Bowm an's capsule and in the connective tissue of fibrocellular crescents. In conclusion, EGFR expression was observed more frequently in disease d than in normal kidneys. The increased incidence of EGFR expression i n FSG, in chronic rejection, in small adhesions with Bowman's capsule and fibrocellular crescents suggest that EGF/EGFR may be correlated wi th a disturbed extracellular matrix production resulting in formation of early sclerotic lesions.