What does a histone antibody level of 3.6 indicate?

From the Guidelines

HISTONE ANTIBODIES 3.6 is indicative of a positive test result for anti-histone antibodies, suggesting the presence of autoantibodies that target histones, which is commonly associated with drug-induced lupus erythematosus or systemic lupus erythematosus (SLE) 1. This finding is significant as it may indicate the presence of an autoimmune condition.

• The value of 3.6 indicates the concentration or titer of these antibodies in the patient's blood, with the specific units depending on the laboratory's testing method.
• Elevated histone antibodies are more prevalent in patients with lupus nephritis than in patients without kidney disease 1.
• However, it is essential to note that anti-histone antibodies can also be found in drug-induced SLE, which may limit their use in disease monitoring 1.
• In the context of SLE monitoring, anti-dsDNA antibodies are preferred for monitoring disease activity, but anti-histone antibodies can play a role in disease monitoring when lupus nephritis is confirmed to be not secondary to any drug treatment 1.
• Patients with positive histone antibodies may require further evaluation, including additional autoimmune testing, medication review if drug-induced lupus is suspected, and possibly rheumatology consultation for proper diagnosis and management.

From the Research

Histone Antibodies

• Histone antibodies, also known as anti-histone antibodies (AHA), are a type of autoantibody that targets histone proteins, which are components of chromatin in cell nuclei 2, 3.
• The presence of AHA has been associated with various autoimmune diseases, including systemic lupus erythematosus (SLE) and rheumatoid arthritis 2, 3, 4.

Clinical Significance

• Elevated levels of AHA have been linked to disease activity and severity in SLE patients 2, 3.
• AHA have also been shown to correlate with inflammatory biomarkers, such as interferon-regulated chemokines, in SLE patients 3.
• In critically ill COVID-19 patients, impaired antibody response, including low levels of AHA, has been associated with organ dysfunction and mortality 5.

Measurement and Interpretation

• The measurement of AHA levels, such as 3.6, may indicate the presence of an autoimmune response or disease activity 2, 3.
• However, the exact interpretation of AHA levels, including 3.6, is not clearly defined in the provided studies and may require further clinical context and evaluation 2, 3, 4.