CD40 Ligand Knockout Mice

CD40 is a 50-kDa glycoprotein expressed on B-cells, monocytes, dendritic cells, follicular dendritic cells, thymic epithelial cells, and certain carcinomas (for review, see ref. 1). Its counterstructure, CD40 ligand (CD40L), is a 33-kDa glycoprotein expressed primarily on activated CD4+ T-cells, but also found on CD8+ T-cells, mast cells, basophils (1), and eosinophils (2). CD40L belongs to the tumor necrosis factor (TNF) superfamily (3), members of which stimulate a broad range of biological functions including proliferation, induction of cytokine secretion, and apoptosis (For review, see ref. 4).