PDCD1 and systemic lupus erythematosus: T peripheral helper (Tph)-like cells in SLE patients such as PD-1hiMAF+ cells, IL-21+IL-10+ cells, and PD-1hiCX3CR1+ cells stimulated with TGF-β3 showed increased proliferation of the cells and elevated expression of PDCD-1, SOX4, and CXCL13 (112).