High-quality, cost-effective strategy for detection of autoantibodies to extractable nuclear antigens

We evaluated methods for the detection of autoantibodies to extractable nuc lear antigens (ENAs) to determine the strategy that yielded the most cost e ffective and clinically meaningful result. We prospectively compared counte rimmunoelectrophoresis (CIEP) with and without serum prediffusion (SPD) and found that SPD significantly improved the quality of precipitation lines. This resulted in a decreased requirement for repeat testing and, consequent ly, was associated with a significant decrease in reagent costs and specime n turnaround time. We also retrospectively compared reactivity by CIEP, CIE P plus SPD, enzyme-linked immunosorbent assay (ELISA), and line immunoassay (LIA) of 52 serum samples that were previously determined to be positive f or ENAs, and we correlated the results with clinical diagnoses. There was s ignificant agreement among CIEP, CIEP plus SPD, ELISA, and LIA for the dete ction of anti-SS-A, anti-SS-B and anti-RNP, In general, CIEP, CIEP plus SPD , and LIA correlated better with the clinical diagnoses than ELISA, even th ough ELISA detected anti-ENAs more often than the other methods. CIEP plus SPD is therefore the most cost effective method for the identification of c linically meaningful ENAs. Based on our experience, we now screen for ENAs by CIEP, and positive samples are then typed by CIEP plus SPD, Samples that are difficult to interpret are then further assessed by an alternative met hod.