The development of systemic lupus erythematosus (SLE) after 38 months of therapy 
with recombinant human interferon gamma (rIFN-gamma) was observed in a patient 
with rheumatoid arthritis. In addition to glomerulonephritis and a butterfly 
rash, previously negative tests for antinuclear, anti-dsDNA and anti-Sm 
antibodies became positive. We assume that rIFN-gamma induced the de novo 
development of SLE in our patient.