Question

1. Describe three ways that an immunofluorescence assay is different to an ELISA that would test for specific antibodies.

Answer 1

indirect immunofluorescence assay (IIFA) and enzyme-linked immunosorbent assay(ELISA) for detecting antinuclear antibodies (ANA) and anti-double-stranded DNA antibodies (anti-dsDNA).

IIFA is more sensitive than ELISA in detecting the total ANA and anti-dsDNA.

The presence and specificity of antinuclear antigens (ANA) is a challenge to a laboratory involved in the diagnosis of connective tissue disease (CTD).

The immunofluorescent technique (IF), once considered the gold standard, is more and more displaced by ELISA.

ELISA can be fully automated and the interpretation does not require the extensive experience needed in IF.

The both techniques are compared does not give unequivocal conclusions that ELISA indeed performs better and the technique is best in the cascade testing of ANA, is given by its clinical value, not only by its technical and logistic performance.

The most commonly used assay is the determination of ANAs (anti nuclear antibodies) by indirect immunofluorescence (IFA) and this method lacks reliable standardisation and is very dependable on the qualification of the observer.

Enzyme Immunoassays (EIA) and Immunoblotting techniques on the contrary attain good standardisation and comparability.