AA GLOMERULAR AMYLOID - AN ULTRASTRUCTURAL IMMUNOGOLD STUDY OF THE COLOCALIZATION OF HEPARAN-SULFATE PROTEOGLYCAN AND P-COMPONENT WITH AMYLOID FIBRILS TOGETHER WITH CHANGES IN DISTRIBUTION OF TYPE-IV COLLAGEN AND FIBRONECTIN

An ultrastructural investigation was undertaken on paraformaldehyde-fi xed Lowicryl resin-embedded human kidneys of three patients with AA am yloidosis to investigate the association of various basement membrane components with amyloid fibrils. An immunogold technique was used and antibodies to serum amyloid A, heparan sulphate proteoglycan, type IV collagen, P component, and fibronectin were applied to human normal an d amyloid glomeruli. The amyloid was identified as AA, and P component was shown to be intimately associated with the fibrils. In addition, heparan sulphate proteoglycan was associated with amyloid in all suben dothelial, subepithelial and intramembranous glomerular basement membr ane deposits, and those throughout the mesengial matrix. This contrast ed with the distribution of the proteoglycan in the normal glomerulus where it was found predominantly on the epithelial aspect of the basem ent membrane and only in the more peripheral regions of the mesangium. The accumulation of heparan sulphate proteoglycan with amyloid result ed in a marked increase in its amount in the glomeruli. The amyloid de posits contained little or no type IV collagen or fibronectin. These f indings demonstrate a strong association of heparan sulphate proteogly can with amyloid and suggest different roles for the various glomerula r basement membrane components in amyloidogenesis.