Maes et al. [101] showed that the prevalences and median values for serum IgM and IgA against LPS of Enterobacteria (Hafnia alvei, Pseudomonas aeruginosa, Morganella morganii, Pseudomonas putida, Citrobacter koseri, Klebsiella pneumonia) were significanty greater in patients with major depression disorder (MDD) than in healthy volunteers. Here, CD40LG is linked to major depressive disorder.