CD2 

CD2 is a transmembrane glycoprotein primarily expressed on the surface of T cells, natural killer (NK) cells, and thymocytes, belonging to the immunoglobulin superfamily. It binds to LFA-3 on the cell surface and plays an important role in immune responses, especially in the formation and organization of the immunological synapse. CD2 enhances T cell activation by binding to LFA-3, thereby boosting immune responses. The expression of CD2 is upregulated on memory T cells and activated T cells, playing a crucial role in the activation of memory T cells.
CD2 also plays a significant role in regulating immune cell functions, particularly in organ transplantation and certain autoimmune diseases. By inhibiting the CD2/LFA-3 co-stimulatory pathway, CD2 can reduce the excessive activation of T cells and NK cells, thereby lowering the risk of graft rejection and prolonging graft survival. Additionally, research indicates that CD2 plays a critical role in NK cell spontaneous cytotoxicity and certain cancer immune responses. Therefore, CD2 presents a broad application potential as an immune-regulatory target, especially in the study of autoimmune diseases and promoting immune tolerance in organ transplantation.