CD4 and autoimmune thrombocytopenic purpura: Recently, follicular helper T (Tfh) cells, an important CD4+T cell subset associated with the development of germinal centers (GC), B cell differentiation, and antibody production, have also been explored in many autoimmune diseases such as GD, systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjögren's syndrome (SS), and immune thrombocytopenia (ITP) [11–15].