The present invention is related to methods of preparing a pharmaceutical formulation comprising a biopharmaceutical drug, which methods allows the modulation of immune responses related to the administration thereof. The formulation comprises a buffer comprising hexanedioic acid or at least one salt thereof, and/or citric acid or at least one salt thereof. The present invention further relates to method of using hexanedioic acid or at least one salt thereof, and/or citric acid or at least one salt thereof, to modulate the immunogenicity of a pharmaceutical formulation, to a pharmaceutical formulation as such, and to methods of modulating or determining immune responses related to the administration of a pharmaceutical formulation (FIG. 4).
