CD40LG and tuberculosis: More recently, close contacts of active TB patients who were persistently negative by IFN-γ release assay and tuberculin skin tests were defined as “resisters” of Mtb (160) and in 2019, a cohort study showed that “resisters” possess IgM and class-switched IgG antibody responses and non-IFN-γ T cell responses to Mtb-specific proteins (161), challenging the rationality of focus on assessing IFN-γ-based immunogenicity in TB vaccine design.