Pattern- and titre-based HEp-2 indirect immunofluorescence to support the evaluation of systemic autoimmune rheumatic disease.
ANA by indirect immunofluorescence is most useful when there is a reasonable pre-test probability of a systemic autoimmune rheumatic disease. Appropriate clinical contexts include suspected systemic lupus erythematosus, Sjögren syndrome, systemic sclerosis, mixed connective tissue disease and idiopathic inflammatory myopathy.
Specimen: Serum · Method: IIFA on HEp-2 cells · Report: Result, titre and fluorescence pattern.
Positive fluorescence is assessed by dilution to convey antibody level and support interpretation.
Nuclear, cytoplasmic and mitotic patterns are described using standardized HEp-2 terminology.
Pattern and titre help guide the most relevant antigen-specific confirmatory tests.
A positive ANA does not establish a diagnosis. Follow-up testing should be selected according to the IFA pattern and the patient’s phenotype. Depending on the clinical question, targeted tests may include anti-dsDNA, an ENA/ANA immunoblot profile and other disease-specific autoantibodies.
For SLE classification, the 2019 EULAR/ACR criteria use ANA ≥1:80 on HEp-2 IFA (or an equivalent test) as an entry criterion. This is a classification threshold, not a stand-alone diagnostic rule.
Low-titre reactivity may occur in healthy individuals and non-rheumatic conditions; indiscriminate screening lowers specificity.
Interpret ANA with the clinical phenotype and, when indicated, disease-specific antibodies and organ assessment.
Serial ANA titres are generally not useful for monitoring disease activity; use condition-specific clinical and laboratory markers.
Important: A negative ANA reduces the likelihood of some ANA-associated systemic diseases, particularly SLE, but does not exclude every autoimmune disorder. If clinical suspicion remains high, select phenotype-specific testing.
Clinical framework: International Consensus on ANA Patterns (ICAP) and the 2019 EULAR/ACR SLE classification criteria. Classification criteria are not diagnostic criteria.
Our pathology team can help with specimen requirements, pattern-directed follow-up and the available ANA immunoblot profile.
