Table 1 Biological activities of complement activation proteins, with relevance to AD.
From: Using animal models to determine the significance of complement activation in Alzheimer's disease
Name | Biological activity |
|---|---|
C1q | Enhances Aβ aggregation [43,44]; may facilitate Aβ clearance [56]; enhances Aβ-induced cytokine secretion by microglia [49] |
C3a | Anaphylatoxin (increases capillary permeability) [155] ; protects neurons vs. excitotoxicity [52] |
C3b | Immune adherence and opsonization [89] (may facilitate Aβ clearance by phagocytic microglia) |
C4a | Anaphylatoxin (weak) [156] |
C5a | Anaphylatoxin; protects neurons vs. excitotoxicity [51]; chemotaxic attraction of microglia [46,47]; inhibits apoptosis 54; increases cytokine release from Aβ-primed monocytes [48] |
C5b-9 | Neurotoxicity [50]; sublytic concentrations may have both pro- and anti- inflammatory activities [157] |