CD40LG and common variable immunodeficiency: In 30 individuals with CVID with known pre-treatment, IgG concentrations, there was no correlation between pre-treatment IgG and sBCMA concentrations (r = 0.13, P = 0.49), but positive correlations were observed between serum IgA concentrations (r = 0.72, P < 0.0001) and serum IgM concentrations (r = 0.55, P = 0.002).