‘Times are Changing’

Switch Over to Automated ANA Testing?

Anti-nuclear antibody (ANA) assay is a screening test used to diagnose or support the diagnosis of various autoimmune rheumatic diseases. The indirect immunofluorescence technique on monolayers of cultured epithelial cells is the current recommended method for ANA assay. However, the technique is time-consuming and requires skilled operators. Automated ANA reading systems have recently been developed, which offer the advantage in terms of faster speed and much ease of performance.

Meronietal, in a recent open access article published in BMC Medicine 2014 (http//www.biomedcentral.com/1741-7015/12/38), has discussed the results and controversies regarding automated assays for ANA. Presently, it appears that at least six commercial systems for the automated reading of ANA IIF are available. They detect ANA based on  arrangement of different hardware modules combined with mathematical pattern—recognition software algorithms which enable fully automated image acquisition, analysis and evaluation of IIF ANA tests. Results can be interpreted as positive or negative and the main IIF pattern can be recognized. In addition, quantitative fluorescence intensity value (equivalent to the endpoint titer) can be obtained:
The reported advantages of these systems include

• Reduced intra-laboratory and inter-laboratory variabilities
• Enhanced correlation between staining patterns with corresponding autoantibody reactivities
• Greater laboratory workflows
• Darkroom no longer required
• Integrated file storage, and easy retrieval of data

Current evidence suggests that there is a good correlation between manual and automated interpretation of ANA IIF assays. The most important result of an ANA assay is a NEGATIVE result. Automated assay methods are accurate in their ability to discriminate between positive and negative results as well as in recognizing the main IIF patterns. Such systems will, therefore, speed up routine performance of these tests and help harmonize interpretation of the results across laboratories.
However, there is a need to have their clinical diagnostic power validated by clinical studies. Currently, newer assay systems are deficient in interpretation of mixed patterns or mixed specificities. These new systems need modifications to improve their ability to recognize mixed fluorescent or less common fluorescent patterns.

References

• Meroni PL, Bizzaro N, Cavazzana I, et al. Automated tests of ANA immunofluorescence as throughput autoantibody detection technology: strengths and limitations. BMC Med. 2014;12:38.
• Agmon-Levin N, Damoiseaux J, Kallenberg C, et al. International recommendations for the assessment of autoantibodies to cellular antigens referred to as anti-nuclear antibodies. Ann Rheum Dis. 2014;73:17–23.