Understanding ANA Profile vs. ANA HEp-2 Cell Profile
Key Distinction
The term "ANA HEp-2 cell profile" refers to the specific testing methodology using indirect immunofluorescence assay (IIFA) on HEp-2 cells, which is the gold standard reference method for ANA detection, while "ANA profile" is a broader term that may encompass various testing methods including automated assays or panels of specific antibody tests. 1
ANA HEp-2 Cell Profile (IIFA Method)
IIFA on HEp-2 cells is the internationally recognized reference standard for ANA screening, providing superior sensitivity (>95% for SLE) and the ability to visualize multiple cellular antigens simultaneously 1, 2
HEp-2 cells allow detection of antibodies directed against both nuclear and cytoplasmic antigens, with the ability to identify specific immunofluorescence patterns (homogeneous, speckled, nucleolar, centromere, cytoplasmic) that guide subsequent testing 1, 3
The method requires serial dilutions and visual interpretation by experienced laboratory personnel, with results reported as both titer (e.g., 1:160) and pattern 1
HEp-2 cell testing detects the full spectrum of autoantibodies, including those that may be missed by automated methods, making it essential when clinical suspicion is high 1, 2
ANA Profile (Alternative Methods)
"ANA profile" may refer to automated methods such as ELISA or addressable laser bead immunoassays that use a limited number of purified or synthetic autoantigens 2, 4
These automated methods offer higher throughput and standardization but are based on a restricted mixture of defined nuclear antigens 1
Tests based on a restricted mixture of defined nuclear antigens should not be referred to as "ANA test" or "ANA screen" according to international consensus 1
Alternative assays may have different false negative and false positive ratios compared to IIFA, and if clinical suspicion is strong and the alternative method is negative, IIFA must be performed 1
Clinical Implications
If you order "ANA profile" without specifying IIFA on HEp-2 cells, you may receive results from an automated method that could miss clinically significant antibodies (such as anti-Jo-1, anti-ribosomal P, or anti-SSA/Ro in some cases) 3
The pattern information provided by HEp-2 cell IIFA enables "reflex testing" - automatic ordering of specific antibody tests based on the observed pattern, improving diagnostic efficiency 3, 2
Laboratories must specify the method used for ANA detection in their reports, as this affects interpretation and clinical decision-making 1, 2
Practical Recommendation
Always request "ANA by IIFA on HEp-2 cells" or "ANA HEp-2 cell profile" as your initial screening test for suspected systemic autoimmune rheumatic diseases, as this provides both the highest sensitivity and critical pattern information 1, 2
Automated methods may be acceptable only if your laboratory has validated that they demonstrate performance equivalent to IIFA 2
Both the titer and pattern must be reported when using HEp-2 cell IIFA to maximize diagnostic value 1, 2
Common Pitfall
- The terminology "anticellular antibodies" (ACA) is now preferred over "antinuclear antibodies" (ANA) in some contexts, as HEp-2 testing detects antibodies to both nuclear and cytoplasmic antigens - isolated anticytoplasmic antibodies were found in 6.5% of positive cases and would be missed if only nuclear staining is reported 5