RESUMO
In our search of new biomarkers for multiple sclerosis (MS), we aimed to characterize the immunoglobulin (Ig) free light chains (FLC) in patients' cerebrospinal fluid (CSF) and serum, and to evaluate the diagnostic utility of FLC monomer-dimer patterns for MS. FLC were analyzed by Western blotting and mass spectroscopy. CSF and serum samples were examined for the presence of oligoclonal Ig bands by a conventional laboratory test for MS. Three distinct pathological FLC monomer-dimer patterns, typical of MS but not of other neurological diseases, were revealed. In 31 out 56 MS patients the highly increased CSF levels of κ monomers and dimers were demonstrated. In 18 MS patients, the increased κ-FLC levels were accompanied by highly elevated λ dimers. Five MS cases showed no significant elevation in κ-FLC, but they displayed abnormally high λ dimer levels. The intensity of the immunoreactive FLC bands was measured to account for κ and λ monomer and dimer levels and their ratios in the CSF and serum. Combined usage of different FLC parameters allowed the determination of the appropriate FLC threshold values to diagnose MS. The developed method showed higher sensitivity and specificity (96% and 90%, respectively), as compared to those of the conventional OCB test (82% and 70%, respectively). Our study highlights the role of the differential analysis of monomeric and dimeric κ- and λ-FLC for the precise diagnosis of MS.
Assuntos
Cadeias Leves de Imunoglobulina/sangue , Cadeias Leves de Imunoglobulina/líquido cefalorraquidiano , Esclerose Múltipla/sangue , Esclerose Múltipla/líquido cefalorraquidiano , Sequência de Aminoácidos , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Western Blotting , Diagnóstico Diferencial , Humanos , Cadeias Leves de Imunoglobulina/química , Cadeias kappa de Imunoglobulina/sangue , Cadeias kappa de Imunoglobulina/líquido cefalorraquidiano , Cadeias kappa de Imunoglobulina/química , Cadeias lambda de Imunoglobulina/sangue , Cadeias lambda de Imunoglobulina/líquido cefalorraquidiano , Cadeias lambda de Imunoglobulina/química , Espectrometria de Massas , Dados de Sequência Molecular , Esclerose Múltipla/diagnóstico , Bandas Oligoclonais/sangue , Bandas Oligoclonais/líquido cefalorraquidiano , Multimerização Proteica , Sensibilidade e EspecificidadeRESUMO
A new procedure of free light chain (FLC) analysis was developed to assist the diagnosis of multiple sclerosis (MS). In this procedure, Western blotting technique was used to analyze monomeric and dimeric FLCs in the cerebrospinal fluid (CSF) and serum of patients with MS and other neurological diseases. The intensity of immunoreactive FLC bands was quantified by a specially developed software. Analysis of the obtained monomer/dimer patterns of κ and λ type FLCs allowed the determination of the diagnostically useful FLC parameters. The combined use of three FLC indices accounting for monomeric FLC-κ level and κ/λ ratio values in the CSF and serum was found to be of promising diagnostic importance for differentiation of MS from other non-MS neurological diseases.
