** function to breakdown C3b hence controlling positive feedback by inhibiting C and preventing the complement cascade from running to exhaustion each time it is activated. Complement receptor 1 (CR1) is present on many cell types especially RBCs; it functions to bind C3d - the breakdown product of C3b – resulting from the action of Factors I and H. On it binds potentially inflammatory immune complexes in plasma; these are then transported to the liver where they are phagocytosed by the hepatic macrophages and removed. A common inflammatory disease resulting from poorly eliminated immune complexes is globerulonephritis. Finally there is the other membrane-associated inhibitor - CD59. This binds the first molecule of C9 when it inserts into a cell membrane. This prevents the polymerisation of C9 obviating pore formation and cell lysis. It acts as a protective mechanism for the host cells.
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** Break down C3b.
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*** Controls positive feedback by inhibiting C3b¯Bb.
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**** Prevents the complement cascade from running to exhaustion each time it is activated.
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* '''Complement receptor 1''' ('''CR1''') is present on many cell types especially RBCs; it functions to bind C3d - the breakdown product of C3b – resulting from the action of Factors I and H. On it binds potentially inflammatory immune complexes in plasma; these are then transported to the liver where they are phagocytosed by the hepatic macrophages and removed. A common inflammatory disease resulting from poorly eliminated immune complexes is globerulonephritis.
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* '''CD59'''
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Finally there is the other membrane-associated inhibitor - CD59. This binds the first molecule of C9 when it inserts into a cell membrane. This prevents the polymerisation of C9 obviating pore formation and cell lysis. It acts as a protective mechanism for the host cells.