Reduced levels of IgM anti-C1-INH367–385, IgM anti-C1-INH367–385 Ac, and IgA anti-C1-INH367–385 Ac were associated with 4.725-fold (p < 0.001, power = 0.737), 4.089-fold (p = 0.001, power = 0.892), and 5.566-fold (p < 0.001, power = 0.848) higher risks, respectively, for the development of SLE compared with HCs, indicating a significant difference after adjustment for age in the logistic regression analysis (Table 1). Here, CD40LG is linked to systemic lupus erythematosus.