CD4 and mycobacterial infectious disease: Indeed, CD4 T cell responses to Mtb are contained in a CXCR3+CCR6+ Th subset, cells that produce IFNγ, IL-2 and TNFα [10], and a mutation leading to the loss of the CXCR3+CCR6+ lineage specific transcription factor RORC leads to mycobacteriosis [26].