Antihistone Antibodies Blood Test

What is the purpose of this test?

Order this Antihistone Antibodies Blood Test, which is used to help in the diagnosis and monitoring of drug-induced lupus erythematosus. Histone antibodies are autoantibodies produced by an individual’s immune system that target their histones. Histones are proteins of eukaryotic cells, predominantly found as DNA complexes. Antihistones are detected in about 30-60% of patients with systemic lupus erythematosus (SLE), but their presence in about 95% of patients with drug-induced lupus is more critical diagnostically. 

Drugs (primarily procainamide and hydralazine) can stimulate the production of histone antibodies in some individuals, resulting in a type of lupus called drug-induced lupus erythematosus. Drug-induced lupus is clinically similar to SLE, except that the former patients do not have kidney or central nervous system involvement and do not demonstrate the multiple types of antinuclear antibodies (ANAs) often found in SLE patients. 

Several drugs have been associated with drug-induced lupus, with the more common examples including:

• Hydralazine
• Isoniazid
• Minocycline
• Penicillamine
• Procainamide
• Quinidine

Additionally, other medications associated with drug-induced lupus include:

• Antibiotics
• Anti-seizure medications
• Anti-tumor necrosis factor (anti-TNF) agents
• Interferon-alpha
• Blood pressure medications
• Methyldopa
• Thyroid medications

When should I order an Antihistone Antibodies Blood Test?

Individuals may order this test if they have experienced symptoms associated with lupus due to using a specific drug. Common signs and symptoms may include:

• Arthritis-like pain in one or more joints
• Fatigue
• Fever
• Muscle pain
• Recurring malar rash (a butterfly-shaped red rash across the nose and cheeks)
• Sensitivity to sunlight
• Weight loss