CD153 is a 39-40 kD type II membrane glycoprotein, also known as CD30 ligand or CD30L. This TNF superfamily member is expressed on activated T cells. CD153 has been reported to stimulate B-cell proliferation, antigen-specific antibody production, polyclonal immunoglobulin secretion, and T cell activation and proliferation. The RM153 antibody inhibits binding of CD153 to CD30.