AN IMMUNOHISTOLOGICAL STUDY OF EPIDERMAL GROWTH-FACTOR RECEPTOR AND NEU RECEPTOR EXPRESSION IN PROLIFERATIVE GLOMERULONEPHRITIS

Many forms of glomerulonephritis including IgA nephropathy are charact erized by mesangial cellular proliferation. Since epidermal growth fac tor is a potent mitogen for Cultured human mesangial cells, we have at tempted to localize and quantify the expression of its receptor in nor mal and abnormal renal biopsies using immunohistochemistry. Using a pa rtiCular antibody (Amersham, clone EGFR1), the epidermal growth factor receptor (EGF-R) was shown to be predominantly localized in the mesan gium of the glomerulus. Visual estimates of intensity of staining sugg ested that expression of this receptor may be increased in some IgA di sease patients with mesangial proliferative glomerular lesions. The ne u receptor which has a 50% homology with EGF-R was, however, absent fr om the glomerulus and cultured mesangial cells did not express detecta ble levels Expression of EGF-R by cultured mesangial cells, as assesse d by immunostaining, was weak and it was not possible to induce detect able upregulation using different cytokines. The factors leading to in creased expression of EGF-R in glomerulonephritis, therefore, remain u nknown. Our findings suggest that signalling via EGF-R may play a role in the pathogenesis of proliferative glomerulonephritis. Despite its homology with EGF-R, the neu receptor is unlikely to have similar impo rtance.