ICOS and myasthenia gravis: The frequency of cTfh2 and cTfh17 cells in CD4+ T cells of myasthenia gravis (MG) patients was significantly increased, and the levels of IL-21, IL-4, and IL-17a produced by ICOShighcTfh cells were significantly higher than those produced by ICOSlowcTfh cells, indicating that high expression of ICOS in MG patients helps to exert the secretion function of Tfh2 and Tfh17 cells [102].