In addition, each

mAb displayed good concordance with Freelite™. The development of precise anti-FLC mAbs, as shown in this study, enables diversification away from existing assay platforms and may lead to improvements in FLC assay design. Current commercial tests, using turbidimetric AG-014699 purchase and nephelometric formats (Bradwell et al., 2001) have a number of well observed limitations. Firstly, these systems are reliant on a separate test for each κ and λ FLC measurement. This introduces inter-test variability and reduces the precision of the κ:λ ratio. Simultaneous measurement of both κ and λ FLCs in our assay removes some of this inter-test variability and should thus provide a more reliable measure of the κ:λ ratio. To our knowledge, this is the first assay to adopt this configuration. From a practical perspective this format is also beneficial as a single test because it is more time and resource efficient, and the sample volume required (< 10 μL) is much lower than typical turbidimetric and nephelometric requirements, Trametinib nmr thus preserving stock

sample volume. A second problem with the format of existing serum FLC tests is known as antigen excess or a ‘hook-effect’ and has been documented elsewhere (Daval et al., 2007 and Levinson, 2010a). This phenomenon occurs when high levels of FLC analyte exceed the number of available antibody binding sites thus reducing or eliminating FLC-antibody aggregates, resulting in a false-negative signal output. Use of a competitive inhibition format in our assay overcomes this problem and such an improvement is likely to improve the reliability of patient diagnosis and monitoring. Indeed, we found no instances where the mAbs ‘missed’ elevated FLC above

100 mg/L (sensitivity of mafosfamide serum IFE), indicating that there were no instances of antigen excess using the mAb assay in serum or in the large numbers of urine samples tested. Our assay also provides a larger dynamic range, better sensitivity, and avoidance of ‘gaps’ seen in the current serum FLC assay in Fig. 4 and Fig. 6, and discussed elsewhere (Bradwell, 2008). In conclusion, we have developed a new method of measuring urine and serum FLC using anti-κ and anti-λ FLC mAbs. This method offers improved sensitivity and reliability over existing methods that rely on sheep polyclonal antisera. Further, the mAbs used in this study demonstrated excellent specificity and identified FLC in 13,090 urine samples tested for the presence of BJ proteins, normal and abnormal FLC levels in 1000 consecutive serums samples, and normal levels of polyclonal FLC from healthy donors.