Proteomic analysis has revealed that MPs from SLE patients contain more immunoglobulins (mainly IgG (some directed against dsDNA), IgA, and IgM (anti-dsDNA, rheumatoid factor)) and complement proteins (C1q, C1s, C3, C4b, and C9) than those from healthy controls, RA patients, or SS patients [83]. This evidence concerns the gene C3 and rheumatoid arthritis.