CD4 and autoimmune disease: According to the production of cytokines and the expression of main transcription factors, CD4+T cells are roughly divided into CD4+T helper (Th) cells such as Th1, Th2, and Th17 cells, which can regulate the inflammatory environment, promote antibody production, control innate immunity and stimulate immune memory, and anti-inflammatory CD4+T groups, namely Treg, which inhibit inflammation, dominant self-tolerance, maintain immune homeostasis and control immune responses to prevent autoimmune diseases (34).