Comparison of analysis of serum free light chains in a cartridge-based protein analyzer Mispa i3 with Roche Cobas 8000.

Serum-free light-chain assays are important in the diagnosis and in monitoring therapeutic responses of plasma cell disorders and are complementary to serum protein electrophoresis. The serum-free light-chain assay detects the light-chain portion of immunoglobulin in its free form with high sensitivity. In combination with serum protein electrophoresis and serum immunofixation electrophoresis, the free light-chain assay serves an important role in predicting disease progression in monoclonal gammopathy. Here, we compare the performance of a cartridge-based system Mispa i3 using Diazyme reagent in comparison to Roche Cobas using Freelite reagent. Both of these reagents use polyclonal antibodies for the detection of serum-free light chains. Mispa i3 is a cartridge-based protein analyzer and has a unique channel shifting technology with both turbidimetric and nephelometric principles for immuno assays. Samples of 196 patients were included in this study, and very good agreement was observed between these two assays. Our data show that even though discrepancies were observed for high concentration samples, they are clinically correlated by the free light-chain ratios. We observed a very good concordance of 89% between these two assays for free light-chain ratios.