Innate Immune Defenses in Human Tuberculosis: An Overview of the Interactions between Mycobacterium tuberculosis and Innate Immune Cells

Figure 3

DCs are the primary antigen presenting cells (APCs) in the immune system and play a central role in activation and differentiation of T cells by presenting antigenic peptides. DCs recognize a variety of M. tuberculosis components directly primarily through TLRs and DC-SIGN. Mtb impacts DC maturation and CD80/CD86 expression via induction of the immunosuppressive IL-10 mediator. Furthermore, engagement of TLRs and DC-SIGN during Mtb infection downregulates MARCH1, a ubiquitin ligase critical for recycling of MHCII on the cell surface. Downregulation of MARCH1 early during infection may play a role in limiting the repertoire of presented Mtb antigens and narrows the adaptive immune response in human TB.