The present invention relates to an antibody preparation comprising modified antibodies of a mammal or derivatives or fragments thereof, specific for an antigen, characterized in that €¢ the antibodies or derivatives or fragments thereof comprise an N-glycan structure free of fucose and xylose, and €¢ the ADCC activity of the preparation is by at least 10% less inhibited in an at least 10% serum solution comprising unspecific antibodies of the mammal than an unmodified antibody preparation of the mammal specific for the same antigen.