Clinical relevance of HEp-2 indirect immunofluorescent patterns: the International Consensus on ANA patterns (ICAP) perspective

Abstract

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 and recurrent miscarriage: Systematic review and meta‐analysis

“…The result is expressed in titers, which are used to describe the antibody concentration in blood. Positive ANA expressed in low titer is commonly found in healthy women, whereas the presence of high titers (>1:160) is strongly associated with autoimmune diseases such as systemic lupus erythematosus (SLE), systemic sclerosis (SSc), and Sjögren's syndrome (SjS) …”

Understanding and measuring human B‐cell tolerance and its breakdown in autoimmune disease

“…Thus, ultra-high-throughput single-cell amplification of paired H and L chains using an emulsion-based linkage PCR can achieve these goals in millions of cells per experiment. 95 Second, the individual antigens used for polyreactivity are highly charged and their binding to mAbs may be abolished by the use of stringent buffers commonly used in ELISA testing. [89][90][91] The latter approach is able to simultaneously analyze the transcriptional profile of each cell and can therefore categorize the functional phenotype of the cell expressing different BCR.…”

“…99 While the precise mechanism of late tolerance remains to be further clarified, the fact that relative to SLE, healthy memory cells contain a very low frequency of B-cells against dsDNA, Smith/RNP and Ro antigens, indicating that at least for these disease-associated antigens, either the generation and/or survival of autoreactive B-cells are impaired in healthy individuals. 95 It is therefore possible that specific autoreactivities might be in fact censored during B-cell development and activation. The contribution of other mechanisms of enforcement of tolerance in human memory cells remains to be fully investigated.…”

“…First, ANA autoreactivity can be frequently seen in healthy subjects and this normal autoreactivity may in fact target self-antigens not recognized by autoimmune patients including DSF-70. 95 Second, the individual antigens used for polyreactivity are highly charged and their binding to mAbs may be abolished by the use of stringent buffers commonly used in ELISA testing. 96 Finally, only dsDNA and insulin binding represent potentially pathogenic autoreactivity in SLE and type I diabetes, respectively.…”

“…101 among the more than 100 antigens detected by lupus serum. 95 It is therefore possible that specific autoreactivities might be in fact censored during B-cell development and activation.…”