The invention relates to a monoclonal antibody or derivative or fragment thereof that is derived from a parental monoclonal antibody, that recognizes the Lewis Y antigen, characterized in that the Fc region or region equivalent to the Fc region of said antibody or derivative or fragment thereof carries a bi-sected hybrid type N-glycosylation pattern and that said antibody shows at least 10 fold increased ADCC and at least 10 % reduced CDC activity.
