Activation of human T cells by FcR nonbinding anti-CD3 mAb, hOKT3γ1(Ala-Ala)

Abstract

Most immune suppressive agents prevent T cell responses by depletion or inactivation of T cells. For example, glucocorticoids and the calcineurin inhibitors, such as cyclosporine A and FK-506, block cytokine gene transcription, preventing the production of T cell growth factors, whereas other agents, such as Campath 1H, cause prolonged depletion of T cells (1-4). While these approaches are very effective in the short term, these effects are not antigen specific and may not persist after the drugs are discontinued. Hence, true immunologic tolerance, in which an immune response does not occur after an immunologic agent is withdrawn, is rarely achieved. In experimental systems, immunologic tolerance requires additional approaches, such as modification of effector cell pool size, T cell stimulatory signals, and importantly, immune regulation (5-8).