The antibody titer of IgM anti-C1-INH367–385 in patients with rheumatoid arthritis (RA) was significantly higher than that in patients with SLE by 1.41-fold (p = 0.0056); however, the IgM anti-C1-INH367–385 Ac titer in patients with SLE was significantly lower than that in HCs by 1.40-fold (p = 0.0095; Figure 4, left panel). This evidence concerns the gene CD40LG and systemic lupus erythematosus.