Clinically, humanized monoclonal antibodies (IgG) and their fragments are used in treatment for patients with various diseases. In patients, even a single dose injection of humanized monoclonal antibody may induce immune response directed against this foreign protein (immunogen).
Individuals with autoimmune diseases, such as rheumatoid arthritis, lupus, etc. produce autoantibodies against human IgG. In circulation, the presence of human antibody against human IgG would bind to the injected humanized antibody therapeutics and therefore diminish the efficacy of either in-vivo diagnosis or treatment. HAHA is likely to increase the risk of anaphylactic complications to subsequent administration of the humanized monoclonal antibody-based therapy.
The presence of HAHA in patient serum or plasma specimens causes both false positive and false negative immunoassay test results depending on assay principles and monoclonal antibodies used in the assay system.