ERVW-1 and systemic lupus erythematosus: We observed large areas of extracellular DNA and coexpression of citrullinated histone H3 and neutrophil elastase when neutrophils were cultured with SLE immune complexes containing ERV-K102 envelope protein, but not when cultured with SLE plasma alone, healthy immune complexes, or immune complexes generated with GST (Fig. 5, G and H).