IGHG3 and tuberculosis: IgG3 is known to activate especially NK cell related functions very efficiently (47), and given the emerging appreciation for a role of NK cells, and potentially antibody dependent cellular cytotoxicity (15), in TB infection (48), these data may point to a functional role of Mtb-specific IgG3 antibodies in anti-microbial control that may contribute to protection against recurrent TB due to NK cell induced functionality.