The indirect immunofluorescence assay (IIFA) on HEp-2 cells is widely used for detection of antinuclear antibodies (ANA). The dichotomous outcome, negative or positive, is integrated in diagnostic and classification criteria for several systemic autoimmune diseases. However, the HEp-2 IIFA test has much more to offer: besides the titre or fluorescence intensity, it also provides fluorescence pattern(s). The latter include the nucleus and the cytoplasm of interphase cells as well as patterns associated with mitotic cells. The International Consensus on ANA Patterns (ICAP) initiative has previously reached consensus on the nomenclature and definitions of HEp-2 IIFA patterns. In the current paper, the ICAP consensus is presented on the clinical relevance of the 29 distinct HEp-2 IIFA patterns. This clinical relevance is primarily defined within the context of the suspected disease and includes recommendations for follow-up testing. The discussion includes how this information may benefit the clinicians in daily practice and how the knowledge can be used to further improve diagnostic and classification criteria.
- antinuclear antibodies
- indirect immunofluorescence
- clinical interpretation
- ANA patterns
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Handling editor Josef S Smolen
Contributors All authors actively participated in the respective workshops in Kyoto and Dresden. They also participated in the discussions of the executive ICAP committee. The draft of the manuscript was made by JD and was commented on by all authors. Final discussions have taken place at the international autoimmunity meeting in Lisbon. Required amendments were made by JD and approved by all authors.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests The ICAP committee is funded by unrestricted educational grants by several in vitro diagnostics companies (for details see www.anapatterns.org/sponsors.php). JD has received lecture fees from Euroimmun and Thermo Fisher. MJF is a consultant to Inova Diagnostics and Werfen International; none of the other authors declare any competing interest.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
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