ENDOTHELIAL-CELLS CULTURED FROM HUMAN BRAIN MICROVESSELS PRODUCE COMPLEMENT PROTEINS FACTOR-H, FACTOR-B, C1 INHIBITOR, AND C4

The inflammatory mediators, cytokines and complement proteins are beli eved to regulate the sequential events during the development of lesio ns secondary to ischaemia and reperfusion. The endothelial cell monola yer of the brain microvasculature is the critical interface between th e blood-borne mediators and brain tissue. The involvement of these cel ls in complement production and regulation has not been well documente d. In the present study, expression of complement proteins (C1 inhibit or, factor H, factor B, C4) by cultured endothelial cells obtained fro m human brain microvessels has been characterized. Interferon gamma up regulates the production of all the complement factors studied. Serine proteases, plasmin and miniplasmin induce the expression of C4, decre ase the level of ELISA detectable C1 inhibitor, and do not affect the production of factors H and B. These data indicate that complement pro teins are expressed locally by the brain microvessels, and may modulat e the inflammatory responses of brain tissue.