OPGL is a key regulator of osteoclastogenesis, lymphocyte development and lymph-node organogenesis

The tumour-necrosis-factor-family molecule osteoprotegerin ligand (OPGL; al so known as TRANCE, RANKL and Cop) has been identified as a potential osteo clast differentiation factor and regulator of interactions between T cells and dendritic cells in vitro. Mice with a disrupted opgl gene show severe o steopetrosis and a defect in tooth eruption, and completely lack osteoclast s as a result of an inability of osteoblasts to support osteoclastogenesis. Although dendritic cells appear normal, opgl-deficient mice exhibit defect s in early differentiation of T and B lymphocytes. Surprisingly, opgl-defic ient mice lack all lymph nodes but have normal splenic structure and Peyer' s patches. Thus OPGL is a new regulator of lymph-node organogenesis and lym phocyte development and Is an essential osteoclast differentiation factor i n vivo