The use of the Congo red-related dye DBACR to recognize the heavy chain-derived abnormality of myeloma immunoglobulins

Abstract.IntroductionThe aim of this study was to differentiate heavy and light chain-derived instability of monoclonal myeloma immunoglobulins by complexation of matched supramolecular dyes. These are composed of several micellar pieces of self-assembled dye molecules which may penetrate the protein interior of the binding locus with polypeptide chains. These dyes were used to elicit, by precipitation, the postulated higher aggregation tendency of the heavy chain derived from its higher hydrophobicity.Materials and MethodsAgarose gel electrophoresis was used to create conditions for dye complexation and to reveal the precipitation.ResultsCongo red derivatives with aromatic ring substitutes, BACR and DBACR, of increased penetrating capability were chosen to provoke the precipitation of abnormal immunoglobulins by displacing association-prone polypeptide chains from the protein interior.ConclusionsThe results of this study confirm the heavy chain-related propensity of some monoclonal immunoglobulins to aggregate and precipitate. The simplicity of the technique may improve clinical diagnosis and facilitate predictions of disease complications.