This study evaluates the forces involved in the adsorption of abagovomab onto an aluminium hydroxide adjuvant in interstitial fluid and the influences of interstitial fluid and its components on this process. Abagovomab is a monoclonal, anti-idiotypic antibody developed as an immunovaccine for the treatment of ovarian cancer. Partial elution of abagovomab by a change in ionic strength indicates that electrostatic interactions influenced adsorption. Studies on the role of phosphate and simulated interstitial fluid on the adsorption demonstrated that ligand exchange is the main force of adsorption. A comparison of the adsorption capacity of abagovomab in the formulation with that in an environment imitating the in vivo environment using simulated interstitial fluid showed the adsorption capacity to decrease, the more the conditions resemble the in vivo environment after subcutaneous or intramuscular administration.