PD-1 and CTLA-4 can play an important role in addressing the issue of
autoimmune diseases. PD-1 is a transmembrane glycoprotein expressed on
T, B, and Dentric cells. This molecule functions as a checkpoint in T
cell proliferation. Ligation of PD-1 with its ligands stimulates the
production of IL-2, IL-7, IL-10, and IL-12 as well as other cytokines,
which can inhibit cell proliferation and inflammation. Today, scientists
attempt to protect against autoimmune diseases by PD-1 inhibitory
signals. In this review, we discuss the structure, expression, and
signaling pathway of PD-1. In addition, we discuss the importance of
PD-1 in regulating several autoimmune diseases, reflecting how
manipulating this molecule can be an effective method in the
immunotherapy of some autoimmune diseases.