Belimumab is a drug that is also known as a monoclonal antibody that restrains the attachment B-lymphocyte protein to receptors on B-lymphocytes, thus averting B-lymphocytes survival and diminishing the activity of B-cell mediated immunity and autoimmune reactions. Lupus is a severe and probably deadly autoimmune condition that can affect almost all parts of the body. Belimumab is the only drug and biological agent for the treatment of systemic lupus erythematosus. It works by reducing the effects of a specific protein that increases in patients with active lupus. Treatment may reduce the symptoms of SLE.