A positive correlation was observed between serum FLC levels and total IgG concentration, total IgA concentration, but not total IgM concentrations in SLE patients (Fig 5A) (r-values of 0.345 (p = 0.021), 0.499 (p = 0.0005) and -0.127 (p = 0.406), respectively). This evidence concerns the gene CD40LG and systemic lupus erythematosus.