THE ROLE OF COMPLEMENT IN DISORDERS OF THE NERVOUS-SYSTEM

The complement (C) system plays important roles in host defense but ac tivation at inappropriate sites or to an excessive degree can cause ho st tissue damage. C has been implicated as a factor in the causation o r propagation of tissue injury in numerous diseases. The brain is an i mmunologically isolated site, sheltered from circulating cells and pro teins of the immune system; nevertheless, there is a growing body of e vidence implicating C in numerous brain diseases. In this brief articl e we review the evidence suggesting a role for C in diseases of the ce ntral and peripheral nervous system and discuss the possible sources o f C at these sites. Some brain cells synthesize C and also express spe cific receptors; some are exquisitely sensitive to the lytic effects o f C. The evidence suggests that C synthesis and activation in the brai n are important in immune defense at this site, but may also play a ro le in brain disease. (C) 1997 Elsevier Science B.V.