Provided is an antibody preparation suitable for intravenous administration in humans comprising IgG, IgA and at least 5% IgM antibodies by weight of the total amount of antibodies, wherein the preparation is prepared from human plasma, wherein the antibody preparation has specific complement activating activity and wherein in an in vitro assay with human serum suitable to determine the ability of the antibody preparation to activate complement unspecifically the antibody preparation generates substantially no C5a and/or substantially no C3a. Further provided are medical uses of the antibody preparation.