CD28 and asthma: The activated T cells in the airway wall are associated with inflammation of asthma [45, 46], and the subsets of T cell antigens have attracted extensive attention by researchers, such as the T cells of CD4+(T helper) [47–51], CD8+ [52–54], CD25+ [55], CD28 [56, 57], CD29 [58, 59], CD39+, and CD73 [60–63].