There was a positive correlation between the patients’ decreased levels of anti-A/B antibodies as detected by SPR and decreased levels of switched memory B cells and IgM memory B cells, and patients with low anti-A/B IgM antibodies had higher levels of naïve B cells, thus showing that SPR anti-A/B antibodies are decreased in parallel with other parameters indicative of the defect in B cell function present in CVID patients (Figure 2). This evidence concerns the gene CD40LG and common variable immunodeficiency.