A 52-year-old man started on procainamide develops arthralgia, fever, and pleuritic chest pain 4 weeks later. Antinuclear antibody testing is positive. Which autoantibody profile best supports drug-induced lupus erythematosus rather than idiopathic SLE?
- A High-titer IgG antibodies against double-stranded DNA with low complement
- B Antibodies directed against histones, with negative anti-dsDNA and normal complement ✓
- C Antibodies against the U1 ribonucleoprotein antigen
- D Antibodies against ribosomal P protein
Correct answer: B. Antibodies directed against histones, with negative anti-dsDNA and normal complement
Explanation
Drug-induced lupus from procainamide, hydralazine, isoniazid, and similar agents features antihistone antibodies in over 95 percent of symptomatic cases, with anti-dsDNA typically absent and complement levels normal, reflecting a different pathogenesis from idiopathic disease. Renal and central nervous system involvement is distinctly uncommon, and symptoms remit after drug withdrawal. High-titer anti-dsDNA with hypocomplementemia is the signature of active idiopathic SLE, particularly lupus nephritis.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.