The present invention provides anti-human ICOS antibodies with increased effector function. The invention further relates to pharmaceutical compositions, immunotherapeutic compositions, and methods using therapeutic antibodies that bind to the human ICOS antigen and that may mediate ADCC, CDC, and/or antibody-dependent phagocytosis (opsonisation) for the treatment and prevention of T cell-mediated diseases and disorders, such as, but not limited to, chronic infection, autoimmune disease or disorder, inflammatory disease or disorder, graft-versus-host disease (GVHD), transplant rejection, and T cell proliferative disorder.
