Monoclonal antibodies to herapin sulphate proteoglycan: development and application to the study of normal tissue and pathological human kidney biopsies - abstract

ABSTRACT

In an attempt to quantify the immuno-histochemical properties of the glomerular basement membrane (GBM), monoclonal antibodies (mAbs) were prepared against heparin sulphate Proteoglycan (HSPG). The HSPG was isolated from bovine glomerulae. Enzyme-linked immuno-sorbent assays (ELISA) and immunoblotting demonstrated that the mAbs reacted with HSPG. Indirect immuno-fluorescence showed that the mAbs stained renal basement membranes (BMs) and BMs in other organs of normal bovine and human tissues in patterns typical of HSPG. Immuno-inhibition studies, and immuno-blotting of heparin lyase digested HSPG, indicated that the mAbs recognizes HSPG core protein. Human kidney biopsies revealed interesting patterns of staining for HSPG. For instance, in kidney biopsies from patients with acute post-streptococcal glomerulonephritis, intact linear staining for HSPG was noted despite abnormal pathological processes shown by widened capillary loops. On the other hand, in membranous and in diffuse proliferative lupus glomerulonephritis, loss of HSPG staining was demonstrated at sites of immuno-deposition of IgG or C3; whereas, increased staining for HSPG was seen in areas of newly formed GBM. Extensive loss of HSPG was seen in areas of glomerular sclerosis and necrosis. In biopsies from patients with minimal change glomerulonephritis and mesangio-proliferative lupus glomerulonephritis, a normal linear GBM distribution of HSPG was noted. The study demonstrates that immunological injury to the HSPG component of the GBM of the kidneys plays an aetiological role in the pathogenesis of proteinuria in man (AU)