The complement system #3

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Immunopharmacology 2000 Aug;49(1-2):171-86

Complement components of the innate immune system in health and

disease in the CNS.

Gasque P, Dean YD, McGreal EP, VanBeek J, BP

Department of Medical Biochemistry, University of Wales College of

Medicine, CF14 4XN, Cardiff, UK.

[Medline record in process]

The innate immune system and notably the complement © system play

important roles in host defense to recognise and kill deleterious

invaders or toxic entities, but activation at inappropriate sites or

to an excessive degree can cause severe tissue damage. C has been

implicated as a factor in the exacerbation and propagation of tissue

injury in numerous diseases including neurodegenerative disorders. In

this article, we review the evidence indicating that brain cells can

synthesise a full lytic C system and also express specific C

inhibitors (to protect from C activation and C lysis) and C receptors

(involved in cell activation, chemotaxis and phagocytosis). We also

summarise the mechanisms involved in the antibody-independent

activation of the classical pathway of C in Alzheimer's disease,

Huntington's disease and Pick's disease. Although the primary role of

C activation on a target cell is to induce cell lysis (particularly

of neurons), we present evidence indicating that C (C3a, C5a,

sublytic level of C5b-9) may also be involved in pro- as well as anti-

inflammatory activities. Moreover, we discuss evidence suggesting

that local C activation may contribute to tissue remodelling

activities during repair in the CNS.