The central component of the complement cascade, C3, is involved in various biological
functions, including opsonization of foreign bodies, clearance of waste material, activation of
immune cells, and triggering of pathways controlling development. Given its broad role in
immune responses, particularly in phagocytosis and the clearance of microbes, a deficiency
in complement C3 in humans is often associated with multiple bacterial infections.
Interestingly, an increased susceptibility to infections appears to occur mainly in the first two …