CD40LG and infection: Finally in the plasma following Mtb challenge, Mpt64-specific C1Q-binding antibodies and PstS1-specific IgM titers following infection that were enriched in protected macaques displayed strong correlations with additional C1Q- and IgM-related features including HspX- and PPD-specific C1Q-binding antibodies, as well as LAM-specific IgM titers (Figure 4C, right), revealing a similar complement fixing IgM signature of protection prior to and following Mtb challenge.