Characterization and localization of basement membrane-associated heparan sulfate proteoglycan in human tissues

A polyclonal antiserum was raised in rabbits against basement membrane heparan sulfate proteoglycan (HSPG) purified from extracts of isolated porcine glomeruli. The antiserum was characterized by enzyme immunoassay, immunoprecipitation, and immunohistological methods. It was shown to recognize specifically the core protein of HSPG from porcine, rat, bovine, and human glomerular basement membrane, but it did not bind to HSPG from guinea pig or rabbit kidney. The affinity-purified antiserum did not cross-react with other basement membrane proteins like laminin, fibronectin, or collagen type IV. Immunohistochemical studies on tissue sections from several human organs revealed specific basement membrane staining, although the intensity of the reaction differed among the organs tested. Whereas glomerular and other capillary basement membranes showed prominent staining with antibody to the core protein of the proteoglycan, those from nerve, skeletal, cardiac, and smooth muscle reacted only weakly. Adipocytes and liver sinusoid walls were not stained. Independent of the extent of HSPG staining the basement membranes of all different tissues tested reacted strongly with an antiserum against type IV collagen.