The Role of Complement in Host Defence and Immune Response

Abstract

The immune system might be compared with a domino: There are individual elements which have to interact in a certain sequence. The sequence may vary considerably, depending on the point of view of the given investigator. These crucial elements within the immune response including antigen, antibody, T- and B - lymphocytes MHC cytokines and the complement system. Complement in one example of those pieces which only could place very well in different steps within the sequence It contributes in the preimmune phase to non-specific host defence and inflammation Alternatively, complement might be regarded as an early component during the induction of the specific immune response and it acts also in final, i.e. effector phase of the immune reaction. Complement is clearly a major humoral defence system It represents a kind of endogenous immunomodulator or immunoregulatory system- In the following, a short overview of this protein system is given focussing the role of the complement protein C3. C3 clearly represents a crucial component within the complement system.