Titration emulation: a computer-assisted technique that simplifies the quantification of anti-dsDNA antibodies using the Crithidia luciliae assay

Titers of anti-double-stranded (ds) DNA antibodies in sera from patients with systemic lupus erythematosus (SLE) using the Crithidia luciliae assay method were compared by conventional titration vs the titration emulation method (ImageTiter1) to evaluate whether the latter assay can replace manual titration. Titers by the two methods were identical or within one dilution in 98% (41=42) of samples. A single sample showed a two-dilution difference. Titration emulation showed a tendency to under-estimate the titer of high titer anti-dsDNA samples, although the difference was small. Titration emulation is a suitable alternative to the conventional titration method, offering an accurate and cost-effective approach to quantification of anti-dsDNA antibodies.