Why adopt the International Consensus on ANA Patterns (ICAP) classification for reporting?

A:The indirect immunofluorescence assay on HEp-2 cells (HEp-2 IFA), commonly known as the antinuclear antibody (ANA) test, is used worldwide in screening for autoantibodies, many of which are valuable biomarkers for the diagnosis of systemic autoimmune diseases. The IFA pattern often provides valuable information about the putative auto-antibody specificity in a sample.

One limitation of reporting HEp-2 IFA patterns is the use of terminology that does not have international consensus. This apparent lack of consensus in HEp-2 IFA pattern descriptors and nomenclature prompted the formation of the ICAP committee in 2014. The goals of ICAP are to promote the harmonization of HEp-2 IFA pattern nomenclature, refine interpretation and test result reports, and emphasize immunological associations and clinical relevance of IFA patterns to optimize and align their usage in clinical care. The ICAP website www.anapatterns.org provides the consensus classification of more than 30 HEp-2 IFA patterns with illustrative images and detailed information on the immunological and clinical relevance of each pattern (Ann Rheum Dis 2019; doi.org/10.1136/annrheumdis-2018-214436).

How can laboratorians begin learning about ICAP?

After free registration on the ICAP website, a training module is available covering an introduction to ICAP and technical recommendations on performing the HEp-2 IFA test. This module also includes a recommendation for dividing IFA patterns into competent- and expert-level patterns. This distinction enables novice users to adopt ICAP in a stepwise manner by focusing on competent-level patterns first, without having to learn all 30-plus patterns at once.

The difference between competent-level versus expert-level patterns is based on two main considerations. First, patterns with greater clinical relevance are classed as competent-level patterns to ensure that all users are able to recognize important clinical implications. Second, some easily recognizable patterns are included in the competent category even if the clinical relevance is less clear at this time. The use of competent-level patterns is strongly recommended for test result reporting.

Are there guidelines on how to report HEp-2 IFA results?

Harmonizing the reporting of HEp-2 IFA results is of paramount importance. To address this need, the ICAP committee published guidelines on how to report HEp-2 IFA test results (Immunol Res 2021; doi: 10.1007/s12026-021-09233-0). These guidelines provide a standard for nomenclature, content, and format of a typical test report.

Is there increasing adoption of the ICAP nomenclature worldwide?

To date, the ICAP website has been translated into 19 languages and has received more than 340,000 views per year from users across more than 180 countries. In the last 3 years, our predominant users are young (18–34 years old, 43%), suggesting that ICAP is reaching the younger generation of IFA users, including students, lab technicians, industry professionals, and clinicians. It’s also worth noting that in 2021, significant revisions were made to the HEp-2 IFA classification tree based in part on feedback from the user community (J Appl Lab Med 2022; doi.org/10.1093/jalm/jfab140).

What are the committee’s future plans for ICAP?

Since there are still unmet needs in this area, ICAP continues to function as a work in progress. For example, only one basic training module has been completed, and the ICAP committee is planning three additional modules to address topics such as multiple, mixed, and composite patterns, as well as the molecular and cellular basis of HEp-2 pattern interpretation. Moreover, the committee is planning collaborative studies to address the characterization of novel HEp-2 IFA patterns and to refine and update the evidence-based clinical significance of rare patterns. To achieve these goals, the committee will continue to meet regularly and solicit input and advice from a wide spectrum of laboratory scientists, clinicians, industry professionals, and regulators.

Edward K.L. Chan, PhD, is coordinator for the ICAP committee and professor of oral biology, anatomy, and cell biology at the University of Florida in Gainesville. +Email: [email protected]