Abstract: Methods and compositions for preventing an immune response to an immunogenic therapeutic agent [i.e. anti-drug antibody (ADA), a.k.a. anti-therapeutic antibody (ATA)] are disclosed. One of the disclosed methods comprises administering an effective amount of an immunosuppressant such as an Interleukin-2 (IL-2) signaling pathway inhibitor, including an antagonist, super agonist or partial agonist to the cytokine IL-2, to the IL-2 receptor (IL-2R), or to IL-2R signal transduction molecules. Inhibitors can be in the form of antibodies or antibody fragments, peptide inhibitors, fusion molecule, small molecules, antibody/small molecule conjugates. Administration of a given inhibitor can decrease the incidence and/or magnitude of an immune response or prevent an immune response, including an antibody response, to a potentially immunogenic therapeutic agent in a non-human primate (NHP). Some of the disclosed methods produce a tolerizing effect in NHPs.