[Complement system--an effector of inflammatory reactions. Possibilities of complement regulation in ischaemic...

Activation of the complement system (C) is an important aspect of the immune reaction, and therefore also of inflammatory response. This review summarizes the known pathways for C activation, including the relatively recently described lectin pathway. We must remember that the complement, like the immune response itself, is a two-edge sword. One side is beneficial to the host, aiming to eliminate pathogens, either free or attached to cells. On the other side, overactivation of C may lead to the destruction of tissues, which is obviously harmful. Thus activation of C must be regulated at each stage of the cascade (early, intermittent, and final), and to this end, act specific inhibitors, which often exist as cellular receptors. A list of diseases in which the complement is over-activated was presented, together with a summary of the currently tested or in-use cascade inhibitors. The most dangerous conditions include ischaemias--heart infarct and brain ischaemia. The crucial point in inhibiting C is the possibility of reducing the area of infarct or ischaemia by fast and effective intervention, aiming to disrupt the cascade chain. It is known that excessive killing by C activation is amplified in ischemic tissue; but that the inhibitors may offer protection. One should be aware that many of these exciting studies are being carried out on animals. However, existing knowledge on the efficacy of C inhibitors should be considered jointly with the current use of statins in human therapy, which, among their pleiotropic actions, also lower the level of C activation.