CD4 and coinfection: HIV/Mtb co-infection clinical studies have demonstrated that HIV preferentially induces an overall reduction in Mtb-specific PBMC production of IL-2 producing peripheral CD4 T cells [41], Mtb-specific IL-17 and Th1 producing cytokines from T cells [42–45], and Th transcription factors (e.g., FoxP3, T-bet) within Mtb-specific CD4 T cells [46].