MAb B-R18 specifically recognizes CD95, also known as Fas, a transmembrane glycoprotein with a MW of 40-45kDa, containing 8kDa of N-glycosidic-linked polysaccharide. It is a receptor for TNFSF6/FASLG, a member of the nerve growth factor receptor/tumor necrosis factor superfamily, mediating receptor-triggered apoptosis. The adapter molecule FADD recruits caspase-8 to the activated receptor. The resulting death-inducing signaling complex (DISC) performs caspase-8 proteolytic activation, which initiates the subsequent cascade of caspases (aspartate-specific cysteine proteases) mediating apoptosis. FAS-mediated apoptosis may have a role in the induction of peripheral tolerance, in the antigen-stimulated suicide of mature T-cells, or both. The secreted isoforms 2 to 6 block apoptosis (in vitro). CD95 antigen is expressed on the surface of various cell types, preferentially on the CD45RAlow CD45ROhigh subset of memory T lymphocytes.