B lymphocyte stimulator protein levels in systemic lupus erythematosus and other diseases.

The size of the known members of the tumor necrosis factor ligand and receptor superfamilies has burgeoned in the past few years. Among the novel tumor necrosis factor ligand and receptor superfamily members recently described is B lymphocyte stimulator (BLyS; Human Genome Sciences, Rockville, MD) protein. By virtue of its ability to promote B-cell survival, expansion, and differentiation, it likely plays an important contributory role in systemic lupus erythematosus pathogenesis and propagation. In addition, it may play a similar role in other systemic immune-based rheumatic diseases, and becomes a legitimate candidate target for antagonist biologic agents.