Description: The 24-31 monoclonal antibody reacts with human CD154, a 39 kDa transmembrane glycoprotein also known as gp39 and CD40 ligand (CD40L). CD154 is a member of the TNF superfamily and is expressed transiently by activated T cells. Through its binding to CD40 on antigen presenting cells including B cells, monocytes/macrophages and dendritic cells, CD154 serves a crucial function in T-APC cognate interaction. CD154 interaction with CD40 transduces signals for T-dependent B-cell activation and induces B cell cycle entry. 24-31 cross-reacts with the cynomolgus monkey CD154.