T memory stem cell characteristics in autoimmune diseases and their promising therapeutic values

Memory T cells are conventionally subdivided into T central memory (T-CM) and T effector memory (T-EM) cells. However, a new subset of memory T cells named T memory stem cell (T-SCM) cells has been recognized that possesses capabilities of both T-CM and T-EM cells including lymphoid homing and performing effector roles through secretion of cytokines such as interleukin-2 (IL-2) and interferon-gamma (IFN-& gamma;). The T-SCM subset has some biological properties including stemness, antigen independency, high proliferative potential, signaling pathway and lipid metabolism. On the other hand, memory T cells are considered one of the principal culprits in the pathogenesis of autoimmune diseases. T-SCM cells are responsible for developing long-term defensive immunity against different foreign antigens, alongside tumor-associated antigens, which mainly derive from self-antigens. Hence, antigen-specific T-SCM cells can produce antitumor responses that are potentially able to trigger autoimmune activities. Therefore, we reviewed recent evidence on T-SCM cell functions in autoimmune disorders including type 1 diabetes, systemic lupus erythematosus, rheumatoid arthritis, acquired aplastic anemia, immune thrombocytopenia, and autoimmune uveitis. We also introduced T-SCM cell lineage as an innovative prognostic biomarker and a promising therapeutic target in autoimmune settings.