Clinically, mouse monoclonal antibodies (IgG) and their fragments are used for in-vivo diagnostic procedures (radionuclides) and treatment for patients with various diseases. In patients, even a single dose injection of murine monoclonal IgG may induce immune response directed against this foreign protein (immunogen). In the circulation, the presence of human antibody against murine IgG would bind to the injected murine IgG and, therefore, diminish the efficacy of either in-vivo diagnosis or treatment. Especially, the HAMA would increase the risk of anaphylactic complications to subsequent administration of the murine IgG based therapy.