Results demonstrated that the mAb assay correlated well with densitometry (representative data in Fig. 3). Given the success of the mAb assay at detecting FLC in urine, the clinical utility of the mAb assay was then assessed in 13,090 unconcentrated urine samples sent to the laboratory for routine FLC analysis between April 2008 and Nov 2010. All samples were also analysed by urine IFE (the gold standard for presence of LC in urine) to assess the specificity of the mAb assay, and to ensure that the mAb assay detected all FLC paraproteins.

All samples were analysed as they arrived in the laboratory. After initial routine analyses, samples were stored Rapamycin solubility dmso at − 20 °C. 2995 samples (22.8%) had monoclonal κ, 1180 samples (9.0%) had monoclonal λ, and 105 samples (0.8%) had poly LC, as detected by IFE. 12,242 of these samples were from patients who had a known immunoglobulin paraprotein in serum by IFE (93.5%), 641 samples had no paraprotein in matched serum, and 207 had no serum IFE diagnosis or no serum available. 3806 samples were received from patients enrolled in myeloma trials and the remaining 9284 samples were non-trial samples. Because two anti-κ FLC and two anti-λ FLC mAbs were used in each test, BMS 354825 the maximal concentration detected by each anti-κ (BUCIS 01

or BUCIS 04) and each anti-λ mAb (BUCIS 03 or BUCIS 09) was chosen as the final urine FLC result. As a means of determining

the specificity of the mAb assay in urine, any results that were immunofixation positive and mAb assay negative (recorded clinically as < 10 mg/L), were classed as discrepant. To ensure that each of the anti-FLC mAbs targeted all FLC epitopes, all discrepant samples were re-tested on the mAb assay and by urine IFE. If a discrepancy remained, a full urine IFE was conducted to exclude the presence of whole paraprotein because initial IFE used anti-sera against LC free and bound. Further investigation of matched serum and patient history was conducted selleck compound where necessary and available. Freelite™ κ and λ FLC assays were conducted on a Roche Hitachi Modular analyser using manufacturer’s instructions. The reported working range of Freelite™ on this instrument from the manufacturer was 3.7–56.2 mg/L for κ FLC and 5.6–74.8 mg/L for λ FLC (Bradwell, 2008). Urine and serum IFE was performed using Hydragel IF 2/4 gels on a Hydrasys analyser according to manufacturer’s instructions (all antisera from Sebia, France). Routine serum IFE comprised a panel of antisera against: bound and free κ and λ LC, IgA, IgM, and IgG. Where necessary, antisera against IgD, IgE, and κ and λ FLCs were also used. Routine IFE on unconcentrated urine comprised a panel of antisera against bound and free κ and λ LC. Where necessary, antisera against IgA, IgD, IgE, IgG, IgM and κ and λ FLCs were used.