Complement in central nervous system inflammation.

The complement system is well represented in the central nervous system. Glial cells and neurons produce or express all of the activation and regulatory proteins and the C3a/C5a receptors. Inhibition of complement activation is protective in experimental allergic encephalomyelitis, the animal model for multiple sclerosis, suggesting possible therapeutic approaches for human disease. New findings indicate that the C3a/C5a receptors are widely expressed in neurons and may modulate neuronal function.