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Clinical Proof-of-Concept

Screening autoantibody profiles in systemic rheumatic disease

The NALIA system has been tested in the multiplex analysis of the multiple autoantibodies that characterize systemic lupus erythematous, a rheumatoid disease.

Methods

The NALIA system consists of conventional 96-well membrane-bottomed plates in which antigens or antibodies are adsorbed onto the underside of the membrane.

Current arrays use a 5X5 format (25 dots/well), which allow 10 analytes to be measured in duplicate: double-stranded DNA (dsDNA), centromere protein B (CENP-B), PCNA, Sm, Sm ribonucleoprotein (Sm-RNP), U1-snRNP, Scl70, SSA/Ro, SSB/La, Jo-1, and controls. The test fluid, control sera, and subsequent reagents are drawn through the membrane. The captured analytes are quantified by monitoring chemiluminescence with a charge-coupled device (CCD) and analyzed with commercial array software.

Results

The assay can detect <20X10³ IU/L of anti-dsDNA. The interwell CV was 10%–14%. There was an 83% concordance (κ = 0.56) between the NALIA results obtained for anti-dsDNA assayed by β-testing in a routine immunology diagnostic laboratory and the results obtained with a conventional ELISA reagent set.

The concordance values for Ro, La, Sm, and RNP were 98% (κ, 0.92), 93% (κ, 0.41), 97% (κ, 0.62), and 97% (κ, 0.73), respectively.

Conclusion

The NALIA approach promises to provide a highly economical platform for a wide range of applications that require assays of multiple analytes. The degree of concordance of our results with a conventional reagent set was no less than that occurring between different commercial products. A sample of serum from a finger stick provides a volume sufficient to perform the array assay.


*Screening Autoantibody Profiles in Systemic Rheumatic Disease with a Diagnostic Protein Microarray That Uses a Filtration-Assisted Nanodot Array Luminometric Immunoassay (NALIA). Clinical Chemistry 54 883-890, 2008