What is the significance of mitotic spindle fibers in a 1:80 Antinuclear Antibody (ANA) test result?

From the Guidelines

In an ANA test with a 1:80 titer showing a mitotic spindle fiber pattern, this indicates the presence of antibodies targeting proteins involved in cell division, which may be seen in some patients with Sjögren's syndrome, systemic lupus erythematosus (SLE), or certain drug-induced conditions, but is not typically associated with major autoimmune diseases. This finding is based on the most recent and highest quality study available, which provides recommendations for the assessment of autoantibodies to cellular antigens referred to as anti-nuclear antibodies 1. The mitotic spindle pattern occurs when antibodies bind to proteins that form the spindle apparatus during cell division, and is relatively uncommon compared to other ANA patterns like homogeneous or speckled patterns. Some key points to consider include:

• A 1:80 titer is considered a low positive result, and in isolation without clinical symptoms, it may not require specific treatment.
• If symptoms of autoimmune disease are present, further testing is recommended, including more specific antibody tests like anti-dsDNA, anti-Ro/SSA, or anti-La/SSB.
• The clinical significance of this finding depends on symptoms and other laboratory findings, so discussing these results with a rheumatologist is important for proper interpretation and management.
• Recent studies suggest that the use of anti-dsDNA autoantibodies in the diagnosis and follow-up of systemic lupus erythematosus should be based on a double-screening strategy using a last-generation SPA in the first place, and subsequently, the CLIFT as the confirmation test 2, 3, 4.
• It is also recommended to include pertinent clinical information in the requests of autoimmunity tests to increase the positive predictive value of ANA detection 4.

From the Research

Mitotic Spindle Fibers in 1:80 ANA Lab Test

• The presence of mitotic spindle fibers in a 1:80 ANA lab test is associated with various autoimmune disorders, including systemic lupus erythematosus (SLE) and rheumatoid arthritis 5.
• Mitotic spindle autoantibodies are reported to occur rarely, but are easily identified during the immunofluorescent detection of anti-nuclear antibodies (ANA) 6.
• The clinical significance of mitotic spindle autoantibodies is not well understood, but studies suggest that they may be associated with rheumatic diseases, such as arthritis, and other conditions, including adenocarcinoma and mesothelioma 6.
• High-titre anti-MSA (>1:80) is more frequently associated with thyroid autoantibodies compared to low-titre anti-MSA (<1:40) or high-titre ANA positive, anti-MSA negative individuals 6.
• The prevalence of mitotic spindle fibers in ANA patterns is higher in females than in males, and is often associated with other uncommon ANA patterns, such as nuclear centromere and nuclear large/coarse speckled patterns 5, 7.

Associated Autoimmune Disorders

• Systemic lupus erythematosus (SLE) is one of the most common autoimmune disorders associated with mitotic spindle fibers 5, 7.
• Rheumatoid arthritis (RA) is also commonly associated with mitotic spindle fibers, as well as other autoimmune disorders, such as Sjögren's syndrome and scleroderma 5, 7.
• Undifferentiated connective tissue disease (UCTD) and chronic idiopathic urticaria (CIU) may also be associated with mitotic spindle fibers, although the clinical significance of these associations is not well understood 7.

Clinical Utility

• The detection of mitotic spindle autoantibodies may provide diagnostic information in autoimmune and other disease conditions, particularly when used in conjunction with other clinical and laboratory tests 5, 7.
• Further evaluation of mitotic spindle autoantibodies and their corresponding antibodies is necessary to fully understand their clinical utility and significance 5, 7.