Are there differences in antigen recognition by mucosal-associated invariant T cells against mycobacterial infection and sarcoidosis?

Mycobacterial infections and sarcoidosis have similar clinical presentations and require careful differential diagnosis, but the etiology differs between these diseases. It has been demonstrated that circulating interferon-γ levels decrease during infection by mycobacteria but increase in sarcoidosis. The involvement of innate-like lymphoid T cells in host immunity against these diseases has also become increasingly evident. Mucosal-associated invariant T (MAIT) cells are involved in innate immunity and are activated when antigens are presented to the T cell receptor through major histocompatibility complex class I-like molecules, namely MR1, by antigen-presenting cells. Notably, MAIT cells produce cytokines, such as interferon-γ, and antigen-derived ligands loaded onto MR1 can act as agonists or antagonists on MAIT cells. Therefore, MAIT cells may discriminate against ligands derived from the causative antigens of mycobacteria and sarcoidosis, potentially contributing to the ridge of the host immune response between these diseases.