The role of the P2X7 receptor in myeloid-derived suppressor cells and immunosuppression.

Myeloid derived suppressor cells (MDSC) are a heterogeneous population of immature myeloid cells expanded and recruited from the bone marrow to the periphery or to a specific site of inflammation/infection. MDSC have been described in different pathological conditions including cancer, infections, autoimmunity and obesity. The main function of MDSC is immunosuppression occurring through different mechanisms such as induction of immunosuppressive cells, impairment of lymphocyte homing, free radical production, depletion of amino acids critical for T cell functions, upregulation of ectoenzymes involved in adenosine production and activation of immune regulatory molecules responsible of T cell anergy. A novel immunosuppressive mechanism MDSC-mediated involves the ATP/P2X7 receptor axis that induces the release of immunosuppressive chemokines/cytokines upon triggering with ATP.