title: Existence of disulfide-bonded IgM-IgA, IgM-IgG and IgM-IgG fragment complexes in one patient.
abstract: The existence of disulfide-bonded immunoglobulin (Ig) complexes of IgM-IgA, IgM-IgG, and IgM-IgG, in addition to a monoclonal IgM (kappa) paraprotein, free kappa chains and fragments of IgG (FIgG), were found in the plasma of a multiple gammopathy patient. This is the first report on the interclass disulfide-bonded Ig complexes. Upon exposure to a dissociating buffer containing 6 M urea, 0.1 M Tris-HCl, pH 8.0, a small portion of the IgM-IgA complexes and most of the IgM-IgG as well as the IgM-FIgG complexes dissociated, but the majority of the IgM-IgA and small amounts of other complexes remained intact. These intact complexes were not the result of antigen-antibody reactions and were apparently held together by disulfide bonds which could be broken into monomeric Ig basic units (H-L)2 and smaller components by mild reduction and alkylation.
mesh_terms: D004220:Disulfides / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D007122:Immunoelectrophoresis; D007070:Immunoglobulin A / Q000032:analysis*; D007128:Immunoglobulin Fragments / Q000032:analysis*; D007074:Immunoglobulin G / Q000032:analysis*; D007075:Immunoglobulin M / Q000032:analysis*; D008875:Middle Aged; D010265:Paraproteinemias / Q000276:immunology*
chemical_list: D004220:Disulfides; D007070:Immunoglobulin A; D007128:Immunoglobulin Fragments; D007074:Immunoglobulin G; D007075:Immunoglobulin M