Immunohistochemical identification of heparan sulphate proteoglycan in secondary systemic amyloidosis.
The distribution of proteoglycans in kidneys from patients with secondary (AA) systemic amyloidosis was investigated. Antisera reacting with the protein cores of chondroitin sulphate proteoglycan (CSPG), dermatan sulphate proteoglycan (DSPG) and heparan sulphate proteoglycan (HSPG) were used in conjunction with the peroxidase-antiperoxidase (PAP) method. HSPG was the only proteoglycan found to be specifically localized to the amyloid deposits. The staining was most intense on the endothelial side of the deposits in both the glomeruli and in the vessel walls. No staining was observed after absorption of the HSPG antiserum with a fraction of the amyloid preparations, corresponding in size to that reported for glomerular HSPG. The possible role of HSPG and endothelial cells in the pathogenesis of the amyloid deposits is discussed.