From the Guidelines
Anti-histone antibodies are indeed positive in both drug-induced and regular lupus, but their prevalence and clinical significance differ between the two conditions. According to the most recent study 1, anti-histone antibodies are more frequently found in patients with lupus nephritis than in those without kidney disease. However, they are also more commonly associated with drug-induced lupus, which can make it challenging to distinguish between the two conditions based on serological results alone.
Some key points to consider when interpreting anti-histone antibody results include:
- The presence of anti-histone antibodies in approximately 95% of drug-induced lupus cases, particularly those induced by medications like procainamide, hydralazine, and isoniazid
- The presence of anti-histone antibodies in about 50-70% of patients with idiopathic SLE
- The difference in antibody prevalence between drug-induced and idiopathic SLE, which can help clinicians distinguish between the two conditions when combined with other clinical features
- The role of anti-histone antibodies in monitoring disease activity, particularly in patients with lupus nephritis who remain anti-dsDNA negative 1
It's essential to consider the clinical context and other diagnostic criteria when interpreting anti-histone antibody results, as the presence of these antibodies alone is not sufficient to diagnose or distinguish between drug-induced and regular lupus. As recommended by the European League Against Rheumatism 1, a comprehensive assessment of patients with SLE should include the evaluation of disease activity, organ damage, quality of life, comorbidities, and drug toxicity.
In terms of monitoring, anti-histone antibodies can play a role in disease monitoring when lupus nephritis is confirmed to be not secondary to any drug treatment 1. However, their use should be guided by the most recent and highest-quality evidence, and clinicians should be cautious when interpreting results in the context of drug-induced versus regular lupus.
From the Research
Anti-Histone Antibodies in Lupus
- Anti-histone antibodies are present in both drug-induced and regular lupus, as shown in studies 2, 3, 4, 5, 6.
- In drug-induced lupus, anti-histone antibodies are often found in the absence of high titers of anti-ds-DNA antibodies, which can help distinguish it from regular lupus 2, 5.
- The presence of anti-histone antibodies in regular lupus is associated with disease activity and certain clinical features, such as Raynaud phenomenon and cytopaenias 2, 4.
- Different drugs can induce distinct patterns of anti-histone antibody reactivity, with procainamide-induced lupus showing strong activity for trypsin-resistant fragments and hydralazine-induced lupus reacting primarily with H3 and H4 6.
Diagnostic Value of Anti-Histone Antibodies
- Anti-histone antibodies can be useful in diagnosing systemic lupus erythematosus (SLE) and drug-induced lupus erythematosus (DILE) 2, 3, 4.
- The diagnostic value of anti-histone antibodies lies in their ability to distinguish between SLE and DILE, as well as their correlation with disease activity and certain clinical features 2, 4.
- However, the prevalence of anti-histone antibodies in DILE may be lower than previously thought, due to the use of modern biological agents that do not elicit these antibodies 3.
Clinical Use of Anti-Histone Antibodies
- Anti-histone antibodies can be measured by enzyme-linked immune-sorbent assay (ELISA) or line immunoassays (LIA), with moderate agreement between the two assays 4.
- The clinical use of anti-histone antibodies is still emerging, with studies suggesting their potential in predicting clinical features of SLE and distinguishing between SLE and DILE 3, 4.
- Further research is needed to fully explore the clinical utility of anti-histone antibodies in SLE and other disorders 3, 4.