Analytical characteristics of the in house ELISA methods

Analytical characteristics of the in house ELISA methods – Table Legend

CoH – fKLC Freelite high control; CoL – fKLC Freelite low control; CSF1, CSF2, CSF3 – pooled CSF samples; S1, S2, S3 – pooled serum samples; 1/10, 1/100, 1/250 – pooled CSF dilutions. Pooled sera as well as Freelite controls were diluted 1/1000. SD – standard deviation; CV % – coefficient of variation. Flebogamma 40 mg/L was added to test maximal theoretical cross-reaction with light chains bound in the IgG. There is, however, no information available whether intravenous immunoglobulin preparations may contain traces of free light chains.
Please note that in Method D, sample S1 was out of the calibration range of the fLLC assay.
Estimated bias is only provided for method E since there is no internationally recognized standard for fLC; hence, Freelite controls were presumed to give the indicated concentrations only in conjunction with Freelite calibrators.
Recovery assays: One of the pooled CSFs and sera was spiked with 10% (vol/vol) of either Bethyl purified monoclonal fLC or Freelite standards to obtain the theoretical concentration indicated (i.e., B16 corresponds to the final concentration of 16 ug/L in the sample). The expected concentration was then calculated as the final theoretical concentration + 0.9 * concentration measured in the non-spiked sample within the same analytical run. Recovery was calculated as 100 * (measured concentration – expected concentration)/expected concentration.