Human IgG enhances complement activation and increases the phagocytosis of MTB by macrophages.42 In a previous study, increased complement activation by BCG has been observed among patients with TB with a high IgG2 to LAM ratio.43 Moreover, IgM, IgG1, IgG3 and IgA have been confirmed to be protective antibodies against MTB. This evidence concerns the gene IGHG3 and tuberculosis.