In terms of developmental physiology, the complement system is the oldest immune system against infections. The complement system, which helps to identify immunocomplexes, is a lytic system for the removal of pathogenic microorganisms.

Complement system markers are used in diagnostics and research. A special field of application is the biocompatibility testing of medical devices and therapeutic agents.

Biocompatibility Testing of Medical Devices and Therapeutic Agents

Materials contained in medical devices have to be tested for complement activity in accordance with ISO 10993 “Biological Evaluation of Medical Devices and Testing for Interaction with Blood”.

Materials used in-vivo (e.g. catheter, stents, heart valves, etc.) should behave inert in the body, they should not decompose, nor cause rejection reactions or significantly affect the metabolism. Moreover, all intravenously applied pharmaceuticals, blood products and infusion solutions should be tested with regard to a direct complement activation.

Also, products created in the new field of tissue engineering which are made from native tissue and cells need to be tested thoroughly with regard to their complement-activating potential prior to clinical use.

Especially in therapies involving monoclonal antibodies, complement activation is triggered via the C1q binding site on the heavy chain of the mouse IgG. Therefore, the class of humanized antibodies was introduced because the use of these antibodies will minimize this activation.