C3 and arthritic joint disease: SRI-4 response rates: 31.6%/71.1%/ 89.5% at week 2/4/12; GC dose ↓; improvement/resolution in rash, alopecia, arthritis, fever, serositis; resolution of leukopenia/ thrombopenia in 94.7/100% of patients, complement C3 and C4 ↑; anti-dsDNA-Abs ↓, proteinuria ↓