Pharmacology notes Interleukin-2 receptor-blocking monoclonal antibodies: evaluation of 2 new agents

The development of immunosuppressive agents with less toxicity and more specificity has led researchers to explore the role of interleukin-2 (IL-2) in the immunosuppression cascade. The IL-2 receptor is composed of at least 3 subunits. One subunit, the a chain, named the Tac antigen, is predominantly expressed on activated T cells. Interleukin-2 facilitates the proliferation of alloantigen-activated T-cell clones by interacting with the IL-2 receptor, a critical step in the process of allograft rejection. For this reason, monoclonal antibody development was directed at this portion of the receptor and was called anti-Tac. Agents such as cyclosporine and tacrolimus target different sites along the immunosuppression cascade. It is thought that the IL-2 receptorblocking monoclonal antibody will produce a synergistic effect when given in addition to current 3-drug regimens (i.e., cyclosporine or tacrolimus plus steroids plus azathioprine or mycophenolate mofetil) (1–3).