Systemic lupus erythematosus (drug induced)

Drugs such as hydralazine may be associated with the development of an SLE-like syndrome.

However, compared to idiopathic SLE, in drug-induced SLE:

• there is no female preponderance
• renal and CNS involvement is uncommon
• anti-ds DNA antibodies are generally absent
• anti-Sm antibodies are generally absent
• anti-histone antibodies are present in more than 95% of cases
• the majority of cases resolve with withdrawal of the drug

People with the HLA-DR3 antigen seem particularly at risk of developing a drug-induced SLE. Such patients are "slow acetylators" - they have a genetically determined inability to acetylate the amine or hydralazine moiety of these drugs.

Nonacetylated metabolites accumulate, bind to nucleoprotein or cellular macromolecules, form an antigenic complex and induce an autoimmune reaction.