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8.2. Overview of commercial FLC assays

Chapter 8

A summary of the main commercial FLC assays that are currently being marketed is shown in Table 8.1.

Supplier Assay Antisera Method Instrumentation Specimen types Intended use Regulatory approval
Binding SiteFreelite Polyclonal Latex-enhanced
immunoassay
Nephelometry,
turbidimetry
Serum, urine,
CSF
Diagnosis and
monitoring of MG
CE-marked
FDA approved
New Scientific
Company
Free light chains kit Polyclonal Antisera-based
immunoassay
Nephelometry,
turbidimetry
Urine, CSF Diagnosis and
monitoring of MG
CE-marked
BiovendorHuman immunoglobulin
free light chains κ and λ ELISA
Monoclonal Sandwich ELISA Microplate reader Serum, plasma,
urine
Research only None
Abingdon HealthSeralite™
(dual kappa and lambda test)
Monoclonal Lateral flow
immunoassay
Test strip reader Serum,
urine
Diagnosis and
monitoring of MG
CE-marked
SiemensN Latex FLC Monoclonal Latex-enhanced
immunoassay
Nephelometry,
turbidimetry
Serum, plasma,
urine
Diagnosis and
monitoring of MG
CE-marked

Table 8.1. A summary of commercial FLC immunoassays. MG: monoclonal gammopathy; ELISA: enzyme-linked immunosorbent assay; CSF: cerebrospinal fluid.

Freelite assays are latex-enhanced immunoassays that utilise sheep polyclonal antisera. They are the only FLC assays that are recommended by name in International Myeloma Working Group (IMWG) guidelines (Section 8.5.4). By contrast, each of the other commercial FLC assays has features that may limit their usefulness. New Scientific Company (NSC), from Italy, manufactures FLC assays that are intended for use with urine/CSF. However, to our knowledge, there are no peer-reviewed publications containing data of NSC assay performance. The Biovendor FLC assays are enzyme-linked immunosorbent assays (ELISAs). Whilst this assay format can achieve high sensitivity, they are intended for research use only. Abingdon Health manufactures lateral flow FLC immunoassays based on monoclonal antibodies, but there is currently only one published study that describes limited clinical data [920].

Siemens N Latex FLC assays are latex-enhanced nephelometric assays [199]. Similar to Freelite sFLC assays, the assays are rapid and have good analytical sensitivity. However, a critical difference between N Latex FLC and Freelite assays is the choice of antisera. Siemens N Latex FLC assays utilise mouse monoclonal antibodies and this can lead to problems when measuring sFLCs; this is further discussed below.