CD40L or CD154 is a membrane glycoprotein and differentiation antigen expressed on the surface of T-cells. The CD40 ligand stimulates B-cell proliferation and secretion of all immunoglobulin isotypes in the presence of cytokines . CD40 ligand has been shown to induce cytokine production and tumoricidal activity in peripheral blood monocytes. It also costimulates proliferation of activated T-cells and this is accompanied by the production of IFN-gamma , TNF-alpha , and IL2 .Synonyms: CD40-L, Tumor necrosis factor ligand superfamily member 5, TNF-related activation protein, TRAP, T cell antigen Gp39, CD154 antigen, sCD40, IGM, IMD3, HIGM1, T-BAM, TNFSF5, hCD40L.