The role of complement in disorders of the nervous system

Abstract

The complement (C) system plays important roles in host defence but activation at inappropriate sites or to an excessive degree can cause host tissue damage. C has been implicated as a factor in the causation or propagation oftissue injury in numer- ous diseases. The brain is an immunologically isolated sitc, sheltered from circulating cells and proteins of the immune sys- tem; nevertheless, there is a growing body of evidence implicat- ing C in numerous brain discascs. In this brief articlc we rcvicw the evidence suggesting a role for C in diseases of the central and peripheral nervous system and discuss the possible sources of C at these sites. Some brain cells synthesise C and also express specific receptors; some are exquisitely sensitive to the lytic effects of C. The evidence suggests that C syr,thesis and activation in the brain are important in immune defence at this site bclt may also play a role in brain disease. .................