Drug-induced pemphigus is mainly caused by drugs containing sulfhydryl (thiol) groups in their molecules.
To understand the serial alteration of anti-desmoglein (Dsg) antibody profile in patients with rheumatoid arthritis (RA) receiving thiol compounds.
Anti-Dsg1 or -Dsg3 antibodies were analysed twice in a 1.6-year interval, in the same series of RA patients.
Eleven of 204 serum samples (5.4%) and 6 of 139 samples (4.3%) from the same RA group showed a positive reaction against Dsg1 or Dsg3 in the first and second screening tests, respectively. The positive rates were higher than those in patients with collagen diseases including systemic lupus erythematosus, Sjögren syndrome, mixed connective tissue disease, and systemic sclerosis. In comparison with the results in the first and second screening tests, one RA patient newly gained anti-Dsg3 antibody, and at least 4 patients lost the antibodies in 1.6 years. Three patients produced antibodies to Dsg1 and/or Dsg3 in a similar fashion as did in the first screening tests. Only one RA serum sample exhibited an intercellular reactivity to human skin or monkey esophagus by immunofluorescence, and another sample bound to a 130 kDa protein suggestive of Dsg3 by immunoblotting. Most anti-Dsg antibodies in RA patients recognized EDTA-resistant epitopes of Dsg different from EDTA-sensitive epitopes recognized by pemphigus sera.
RA patients receiving any of the thiol compounds may gain autoantibodies to non-conformational epitopes of either Dsg1 or Dsg3, and that such autoantibodies alone are not capable of inducing acantholysis.