**2.3. IL-2 receptor blockers (IL-2RA)**

IL-2 receptor blockers, Basiliximab (Simulect) and daclizumab (Zenapax) are humanized anti-CD25 monoclonal antibody preparations. They are targeted against the α-chain (CD25) of the IL-2 receptor. Rather than working by lymphocyte depletion, these agents block IL-2 signaling which is required for T-cell growth, differentiation and expansion. Because both agents are derived from mice and partly humanized, they cause far less infusion reactions compared to rATG. Daclizumab is currently not available for use in United States. Basiliximab is used in the U.S. and is typically administered as 20mg intravenous infusion intraoperatively with subsequent doses given on the third or fourth post operative day. Neither drug has major side effects. Risk of infection and lymphoma is far less than that of lymphocyte depleting agents.
