title: Immunoglobulin-free light chain monomer-dimer patterns help to distinguish malignant from premalignant monoclonal gammopathies: a pilot study.
abstract: Multiple myeloma (MM) and AL amyloidosis (AL) are two malignant forms of monoclonal gammopathies. For the purposes of prognosis and treatment, it is important to distinguish these diseases from the premalignant forms of monoclonal gammopathies, such as monoclonal gammopathy of unknown significance (MGUS) and smoldering myeloma (SMM). Routine serum/urine tests for monoclonal protein are insufficient for differential diagnosis. Thus, invasive procedures, such as tissue aspiration or biopsy, are applied. In this study, we aimed at characterization of serum-free light chain (FLC) monomer-dimer patterns to distinguish the malignant from the premalignant forms of monoclonal gammopathies. A quantitative Western blotting was applied to estimate the FLC monomer and dimer levels in AL, MM, MGUS, and SMM patients, and in control subjects (healthy individuals and patients with AA amyloidosis). AL and MM patients displayed an abnormally increased dimerization of monoclonal FLC, accompanied by higher clonality values of FLC dimers, as compared to that of monomers. These abnormalities of FLC patterns were not observed in patients with MGUS, SMM, AA amyloidosis, and healthy individuals. Analysis of FLC patterns helped to differentiate AL and MM from MGUS and SMM, a goal difficult to achieve using routine serum tests. Also, our technique might serve as a complimentary diagnostic tool in the cases with suspected AL amyloidosis, where the diagnosis of MM is excluded, while the results of amyloid typing by routine immunohistochemical techniques are inconclusive.
authors.affiliation: Laboratory of FMF and Amyloidosis, Heller Institute of Medical Research, Sheba Medical Center, Tel Hashomer, Israel.
authors.forename: Batia
authors.initials: B
authors.lastname: Kaplan
authors.forename: Sizilia
authors.initials: S
authors.lastname: Golderman
authors.forename: Boris
authors.initials: B
authors.lastname: Aizenbud
authors.forename: Konstantin
authors.initials: K
authors.lastname: Esev
authors.forename: Olga
authors.initials: O
authors.lastname: Kukuy
authors.forename: Merav
authors.initials: M
authors.lastname: Leiba
authors.forename: Avi
authors.initials: A
authors.lastname: Livneh
authors.forename: Ilan
authors.initials: I
authors.lastname: Ben-Zvi
mesh_terms: D000686:Amyloidosis / Q000097:blood / Q000175:diagnosis*; D015153:Blotting, Western; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000097:blood*; D008998:Monoclonal Gammopathy of Undetermined Significance / Q000097:blood / Q000175:diagnosis*; D009101:Multiple Myeloma / Q000097:blood / Q000175:diagnosis*; D010865:Pilot Projects; D055503:Protein Multimerization; D012680:Sensitivity and Specificity
chemical_list: D007147:Immunoglobulin Light Chains