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背景
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Factor H is a fluid phase complement regulatory protein consisting of a single peptide chain of 20 short consensus repeat segments or CCP’s with a molecular weight of approximately 155 KD. 1 Factor H regulates the alternative pathway of the complement system by modifying activity of the “feedback loop.” It does this in three ways. First, it is a co-factor for the serine protease Factor I, which cleaves C3b to iC3b. iC3b has no hemolytic or amplification function, but may be bound by complement receptors. Second, Factor H prevents the formation of and accelerates the disassociation of the alternative pathway C3 convertase, C3bBb from cell surfaces. Finally, Factor H binds to polyanions on host cell surfaces and tissue matrices, such as basement membranes, blocking deposition of C3b. This later activity is leveraged by many pathogens as a mode of complement evasion. 2
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參考資料
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1、Pangburn M.K. Differences between the binding sites of the complement regulatory proteins DAF, CR1 and Factor H on C3 Convertases, J Immunol 136:6, 1986.
2、Kraiczy P, Würrzner, R. Complement escape of human pathogenic bacteria by acquisition of complement regulators, Mol Immunol 43:31-44, 2006.
3、Atkinson, J.P., et al. Complement factor H and the hemolytic uremic syndrome, JEM 204:6, 1245-1248, 2007.
4、Sivaprasad, S. and Chong, N.V. The Complement system and age-related macular degeneration, Eye 1-6, 200
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