ANA Patterns

AC-5 - Nuclear large/coarse speckled


Previous Nomenclature	spliceosome/nuclear matrix
Description	Coarse speckles across all nucleoplasm. The nucleoli may be stained or not stained. Mitotic cells (metaphase, anaphase, and telophase) have the chromatin mass not stained. e.g. anti-Sm, anti-U1 RNP
Antigen Association	hnRNP, U1RNP, Sm, RNA polymerase III

Clinical Relevance
First level information
About Clinical Relevance & List of Abbreviations

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Present to a varying degree in distinct SARD, in particular SLE, SSc, MCTD, SSc-AIM overlap syndrome, and UCTD (i.e, patients with rheumatic symptoms without a definite SARD diagnosis) (29)

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If SLE is clinically suspected, it is recommended to perform follow-up tests for anti-Sm and anti-U1RNP antibodies; these antigens are commonly included in the routine ENA profile; anti-Sm antibodies are included in the classification criteria for SLE (16, 30, 31)

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If SSc is clinically suspected, it is recommended to perform a follow-up test for anti-RNApol III antibodies (e.g., SSc profile*); the anti-RNApol III antibodies are included in the classification criteria for SSc (8)

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If MCTD is clinically suspected, it is recommended to perform a follow-up test for anti-U1RNP antibodies; the antigen is commonly included in the routine ENA profile; anti-U1RNP antibodies are included in the diagnostic criteria for MCTD (32)

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If the SSc-AIM overlap syndrome is clinically suspected, it is recommended to perform follow-up tests for anti-U1RNP and anti-Ku antibodies; these antigens are included in the routine ENA profile (U1RNP), or in disease specific immunoassays (Ku, i.e., inflammatory myopathy profile* and SSc profile*) (26, 33)

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In non-SARD individuals in the general population, the presence of the AC-5 pattern is not associated with the autoantigens mentioned above and most often concerns low antibody titers

*Availability of the inflammatory myopathy profile, the SSc profile and the (extended) liver profile may be limited to specialty clinical laboratories.

First level information references

van den Hoogen F, Khanna D, Fransen J, et al. 2013 classification criteria for systemic sclerosis: an American College of rheumatology/European League against rheumatism collaborative initiative. Ann Rheum Dis 2013;72:1747-55.

16.

Petri M, Orbai AM, Alarcón GS, et al. Derivation and validation of the systemic lupus international collaborating clinics classification criteria for systemic lupus erythematosus. Arthritis Rheum 2012;64:2677-86.

26.

Betteridge Z, McHugh N. Myositis-specific autoantibodies: an important tool to support diagnosis of myositis. J Intern Med 2016;280:8-23.

29.

Northway JD, Tan EM. Differentiation of antinuclear antibodies giving Speckled staining patterns in immunofluorescence. Clin Immunol Immunopathol 1972;1:140-54.

30.

Satoh M, Fritzler MJ, Chan EKL. Antihistone and antispliceosomal antibodies. In: Lahita RG, Tsokos G, Buyon JP, et al, eds. Systemic lupus erythematosus. San Diego: Academic Press, 2011: 275-92.

31.

Satoh M, VÃ¡zquez-Del Mercado M, Chan EK. Clinical interpretation of antinuclear antibody tests in systemic rheumatic diseases. Mod Rheumatol 2009;19:219-28.

32.

Sharp GC, Irvin WS, Tan EM, et al. Mixed connective tissue disease--an apparently distinct rheumatic disease syndrome associated with a specific antibody to an extractable nuclear antigen (ENA). Am J Med 1972;52:148-59.

Second level information

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Occasionally, autoantibodies revealing the AC‐5 pattern are reactive with RNP other than U1RNP, for instance U2RNP (associated with SSc‐AIM overlap syndrome) or U11/U12RNP (associated with SSc); these autoantibodies can be detected by immunoprecipitation (13, 14).

Note: Specific immunoassays for these autoantibodies are currently not commercially available.

Second level information references

13.

Mimori T, Hinterberger M, Pettersson I, et al. Autoantibodies to the U2 small nuclear ribonucleoprotein in a patient with scleroderma-polymyositis overlap syndrome. J Biol Chem 1984;259:560-5.

14.

Fretig N, Domsic RT, Rodriguez-Reyna T, et al. Anti-U11/U12 RNP antibodies in systemic sclerosis: a new serologic marker associated with pulmonary fibrosis. Arthritis Rheum 2009;61:958-65.

FAQ

IFA pattern changed from coarse granular to homogeneous

Question: The HEp-2 IFA pattern of a patient has changed from coarse granular to homogenous after 6 months. Is it possible?

With all things being equal, same slide manufacturer with same slide lots, same conjugate, and same serum dilution to ensure there are no technical issues, HEp-2 IFA patterns can change over time. This may include a change from no detectable pattern (AC-0) to any AC pattern and vice-versa. Many factors such as disease progression or overlap syndrome, new interventions (drugs, biologicals), new exposures (infectious disease, cancer, etc.) can also affect such changes. It is important to know if the end-point titer also changed (increased or decreased by at least 2 dilutions).
What is the immunological basis for changes in HEp-2 IFA status along the course of SLE? Autoantibody levels do fluctuate along the disease course. Some of them (i.e., native DNA and nucleosome, for example) may fluctuate in relation to disease activity, while others (i.e., anti-Ro60 and anti-Sm) appear to fluctuate independently of disease activity.
Can HEp-2 IFA temporal changes be related to disease activity? Most people would say â€œnoâ€, but the answer is not so simple. A recent study from the Andrade lab evaluated 269 SLE patients regarding their HEp-2 IFA titer and pattern in a transverse (active x intermediary x inactive disease activity) and prospective (change in disease activity status in the same patient along 1-year follow-up) (1). The report showed that patterns and titer change can change and there was some association with disease activity status. High titer and the AC-1 pattern were associated with active disease, whereas low titer and the AC-4 pattern were associated with disease remission. Interestingly, the diagnostic performance (ROC curve AUC) of HEp-2 titer for the definition of disease activity was in the range of traditional disease activity biomarkers (anti-dsDNA, anti-nucleosome) and much greater than C3 and C4. However, the HEp-2 IFA is not recommended as a test for monitoring SLE disease activity. Similar conclusions may apply to other ANA-related rheumatic diseases.
Thus, coming back to the index case, the change from AC-5 to AC-1 may indicate the appearance of anti-nucleosome and/or anti-dsDNA antibodies. It is recommended to be aware of these autoantibodies and possible disease flare.
1. Prado MS, Dellavance A, Rodrigues SH, Marvulle V, Andrade LEC (2020) Changes in the result of antinuclear antibody immunofluorescence assay on HEp-2 cells reflect disease activity status in systemic lupus erythematosus. Clin Chem Lab Med 58:1271-1281. DOI: 10.1515/cclm-2019-0638

Date: October 11, 2021