A rapid ELISA test for detection of human paraproteins

Summary: A rapid ELISA test for detection, characterization and quantification of human paraproteins was developed. The proposed method is a sandwich ELISA, where the capture antibody is specific for a given heavy chain (γ, α or μ) and the labelled antibody is specific either for κ or for λ light chain. Both standard and patient sera are tested with all six possible antibody combinations. Each paraprotein produces a significant increase in titre (as compared with standard) only when tested with the relevant pair of antibodies. This enables the determination of the isotype and light chain type of the paraprotein and the evaluation of its relative quantity in patient serum. The accuracy of the assay (relative deviation) varies from 0.04 for γλ to 0.19 for ακ. The cut-off values for each type of polyclonal immunoglobulin were determined with 200 healthy donor sera. 103 patient sera were analysed. ELISA data are in good agreement with M-component and other clinical data.