The present invention provides methods of treating, preventing or ameliorating the symptoms of T cell-mediated immunological diseases, particularly autoimmune diseases, through the use of anti-CD3 antibodies. In particular, the methods of the invention provide for administration of antibodies that specifically bind the epsilon subunit within the human CD3 complex. Such antibodies modulate the T cell receptor/alloantigen interaction and, thus, regulate the T cell mediated cytotoxicity associated with autoimmune disorders. Additionally, the invention provides for modification of the anti-CD3 antibodies such that they exhibit reduced or eliminated effector function and T cell activation as compared to non-modified anti-CD3 antibodies.