TARGETING HUMAN IL-2 RECEPTORS FOR DIAGNOSIS AND THERAPY

The high-affinity interleukin-2 receptor (IL-2R) is a multichain recep tor with at least three IL-2 binding chains: IL-2R alpha (55 kDa) boun d by the monoclonal antibody anti-Tac, IL-2R beta (75 kDa) and IL-2R g amma (64 kDa). The IL-2R alpha also exists as a naturally occurring so luble molecule (sIL-2R alpha). We target the IL-2R for immune interven tion since resting normal cells do not express the high-affinity IL-2R , whereas this receptor is on some cells in certain lymphoid neoplasia s, select autoimmune disorders, and in individuals rejecting organ all ografts. Treatments have included unmodified murine anti-Tac and radio isotopes conjugated to murine anti-Tac. Our emerging understanding of the IL-2R system continues to open possibilities for more specific imm une intervention.