Abstract

IgG antibodies are the primary mediators of protective humoral immunity against pathogens and have been used therapeutically for over a century. They were first used as antitoxins for the treatment of infectious diseases in the pre-antibiotic era. Today, hyperimmune sera from human donors recovering from infection with specific viruses, such as hepatitis B, cytomegalovirus, and varicella zoster, are used to provide protective immunity to susceptible populations. Moreover, tumor specific antibodies have been successfully used in human cancer therapy. Besides these protective activities, IgG autoantibodies are the principal mediators of autoimmune diseases such as immune thrombocytopenia (ITP), autoimmune hemolytic anemia (AHA), and systemic lupus erythematosus (SLE). The presentation will discuss which molecular and cellular factors influence IgG activity and how we can use this knowledge to enhance the therapeutic and block the self-destructive activity of IgG molecules. Moreover, a short outlook into novel humanized mouse models for understanding how human IgG molecules function in vivo will be provided.