Non-neutralizing type I/II/III anti-IFN Abs can also be present in serum and urine from SLE patients (50–60%), and among them, the detection of type II anti-IFN Abs is associated with elevated anti-dsDNA Ab levels, C3/C4 complement consumption, and SLE disease activity [54,55]. This evidence concerns the gene C3 and systemic lupus erythematosus.