PROTEIN CONSTITUENTS OF AMYLOID DEPOSITS IN BETA-2-MICROGLOBULIN AMYLOIDOSIS

Beta 2-microglobulin is the main protein constituent of hemodialysis-r elated amyloidosis. However, other proteins are present in amyloid dep osits in addition to beta 2-microglobulin. We have studied the protein constituents of amyloid deposits surgically removed from 15 dialysis patients in renal replacement therapy. The proteins were characterized by sodium dodecylsulfate polyacrylamide gel electrophoresis and two d imensional gel electrophoresis (2D-PAGE). The identification of the pr oteins was performed by immunological techniques (Western blotting, im munohistology and electron microscopy with immunogold labelling). The analyses showed the presence of globin chains, alpha 2-macroglobulin, amyloid P component, albumin, hemopexin and lambda and kappa light cha ins of immunoglobulins in amyloid deposits. 2D-PAGE confirmed that bet a 2-microglobulin from amyloid deposits consisted of four or more isof orms. Although the pathogenesis of dialysis-related amyloidosis is not completely understood, it seems highly unlikely that modifications in beta 2-microglobulin entirely explain the amyloid fibril formation. T herefore, in the study of the pathogenesis of amyloidosis, it appears important to take into account all the constituents of amyloid deposit s. A possible role for the proteins reported here should not be neglec ted and further studies aiming to precise their putative participation could provide new insights in the understanding of the mechanisms ind ucing amyloid fibril formation.