The content of free light chains of immunoglobulins kappa and lambda and also ratio of their concentrations in blood serum are important diagnostic and prognostic markers in case of monoclonal gammopathy. The technique FreelightTM based on nephelometric detection of free light chains using polyclonal antibodies is one of common modes of detection of free light chains. The actual study was carried out with purpose of validating of national test-system for detection of level of free light chains in blood serum using technique of enzyme-linked immunosorbent assay. The samples of blood serum were taken from 89 healthy donors and 165 patients with monoclonal gammopathy. To detect the level of free light chains enzyme-linked immunosorbent assay testsystem "Polygnost" was used based on application of monoclonal a ntibodies. The number of analytical characteristics of reagents set was determined including limit of detection and range of linearity. The limit of detection of free light chains using enzymelinked immunosorbent assay test-system was two times lower than claimed by manufacturer of nephelometric set "FreelightTM". Hence, analytical characteristics of enzyme-linked immunosorbent assay set make it possible to detect the level of free light chains within range of standard values. The reference limits were established concerning concentration of free light chains kappa (3.25-15.81 mkg/ml), free light chains lambda (3.23-28.05 mkg/ml) and their ratio (0.3-1.9) in blood serum that factually matched the recommended intervals for "FreelightTM" set. In patients with monoclonal gammopathy the level of free light chains was reliably higher (p<0.01) as compared with control group of healthy donors. In case of paraproteinemia reliable alteration (p<0.01) of ratio free light chains kappa/free light chains lambda was observed in comparison with control group. The results of actual study testify that national enzyme-linked immunosorbent assay set has good analytical and diagnostic characteristics and it can be used in laboratory practice.
Keywords: enzyme-linked immunosorbent assay; monoclonal gammopathy; paraprotein.