title: Identification and quantification of a monoclonal IgM euglobulin: pitfalls and methodologic instruction.
abstract: In a patient with Waldenström's macroglobulinemia routine agarose gel electrophoresis and immunofixation disclosed an IgM-kappa M-component with beta-mobility, but failed to unveil a major monoclonal IgM-kappa euglobulin. This, however, was demonstrated when the procedures were performed in a buffer with NaCl-ion-strength of 0.1 M. Similarly, IgM quantification by routine nephelometry and electroimmunoassay led to dramatically inconsistent results. By a simple agarose gel electrophoresis in NaCl 0.1 M the IgM euglobulin was quantified proportional to the serum concentration of albumin. The identification and classification of an M-component, being exceedingly important diagnostically, may be missed, when solely routine electrophoresis and immunofixation is employed. As regards the quantification of M-components, these are not merely pathologic immunoglobulins nosologically. Also, biochemically they differ from normal, polyclonal immunoglobulins, resulting in immunological techniques being inapplicable for their quantification. For quantitative purposes, a simple, comparative agarose gel electrophoresis is described.
mesh_terms: D000368:Aged; D000911:Antibodies, Monoclonal; D004587:Electrophoresis, Agar Gel / Q000379:methods; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007075:Immunoglobulin M / Q000302:isolation & purification*; D007145:Immunoglobulin kappa-Chains / Q000302:isolation & purification*; D008297:Male; D012712:Serum Globulins / Q000302:isolation & purification; D008258:Waldenstrom Macroglobulinemia / Q000097:blood* / Q000175:diagnosis
chemical_list: D000911:Antibodies, Monoclonal; D007075:Immunoglobulin M; D007145:Immunoglobulin kappa-Chains; D012712:Serum Globulins