BLyS: Member of the tumor necrosis factor family and B lymphocyte stimulator

The tumor necrosis factor (INF) superfamily of cytokines includes both solu ble and membrane-bound proteins that regulate immune responses. A member of the human TNF family, BLyS (B Lymphocyte stimulator), was identified that induced B cell proliferation and immunoglobulin secretion. BLyS expression on human monocytes could be up-regulated by interferon-gamma. Soluble BLyS functioned as a potent B cell growth factor in costimulation assays. Admini stration of soluble recombinant BLyS to mice disrupted splenic B and T cell zones and resulted in elevated serum immunoglobulin concentrations. The B cell tropism of BLyS is consistent with its receptor expression on B-Lineag e cells. The biological profile of BLyS suggests it is involved in monocyte -driven B cell activation.