Anergy is a state of nonresponsiveness to antigen.  T cells require two signals to be come activated: one antigen-specific signal and one non-specific costimulatory signal.  Antigen recognition in the absence of costimulation inactivates naïve T cells.  The inactivated, or anergic, T cells are incapable of proliferating and differentiating into effector cells when they encounter antigen.  The goal of Anergix therapy is to induce a state of nonresponsiveness in the specific T cells responsible for autoimmune disease.  In the case of multiple sclerosis this would mean T cells specific for the myelin antigens (MBP, PLP, MOG) which have been implicated in the disease.