CD28 and cyclic hematopoiesis: They can promote the expression of IL-2 and may positively regulate (CD27 on IgD-CD38+ B cells) and (CD27 on switched memory B cells)/CD244 via the STAT5 and MTORC1 pathways, while negatively regulating (CD33dim HLA-DR+ CD11b- Absolute Count)/IL-18 and (CD28+ CD4- CD8- T cells %T cells)/OPG, thereby facilitating the progression of CH (Figure 6).