Interlaboratory study of free monoclonal immunoglobulin light chain quantification

Abstract

The study revealed several weak points in the methodology, including the need for a uniform sample dilution procedure. Interlaboratory reproducibility was comparable with values achieved in the NEQAS programme. Because the κ/λ ratio cannot be measured with high precision, κ and λ FLC concentrations should be used where possible. Due to its impact on the clinical management of patients with gammopathy, FLC quantification needs to become a part of the regular quality control cycle in myeloma centres.

Multicentered patient‐based evidence of the role of free light chain ratio normalization in multiple myeloma disease relapse

“…Parameters of interest were negative immunofixation in two consecutive samples, less than 5% of plasma cells in the bone marrow, no plasmocytoma, negative urine immunofixation , and occurrence of relapse. For all patients, the samples for FLCr evaluation were collected at time of reaching complete remission as a part of a new standard evaluation in the Czech Republic . The samples for FLCr were obtained at standard timepoints after ASCT at D+28, D+100, or whenever CR was reached.…”

“…The biochemical analysis was completed according to currently established methods . For all FLC analysis, the standard FreeLite ™ (Binding Site, Birmingham, United Kingdom) method was used.…”

Defining the impact of individual sample variability on routine immunoassay of serum free light chains (sFLC) in multiple myeloma

“…This needs to be studied. Furthermore, there is growing evidence of considerable interlaboratory and interplatform variability in measurement and EQA distributions (http://www.immqas.org.uk) which must be taken into account. Previous publications acknowledge some of these issues, but more recent data suggest that non‐linear dose–response relationships affect significant numbers of patients .…”

Analytical performances of SPAplus® turbidimeter for the dosage of immunoglobulins and beta-2 microglobulin in serum

“…Un sérum présentant un taux élevé en chaînes légères libres lambda a présenté un effet de zone sur l'Immage ® 800, donnant une valeur faible erronée, alors que le SPAPLUS ® le détectait supérieur à la gamme de mesure et relançait spontanément une vérification avec une dilution supérieure de l'échantillon de sérum. À l'inverse, un échantillon avec un taux élevé en IgD (évalué par immunodiffusion radiale) a présenté un effet de analyseurs ont déjà été rapportées [15,16], y compris entre le SPAPLUS® et 'immunonéphélémètre BNII® [17]. Ces différences pourraient être dues aux lots de réactifs, au fait que le dosage de certaines chaînes légères libres monoclonales n'est pas linéaire quand on les dilue [18] des cuvettes) durent environ dix minutes.…”