In summary, co-deposited IgA1 antibodies maximized the efficiency of the complement system, transported their covalently bound complement fragments to specific antigens and sustained the effective deployment of IgG1 antibodies directed to those same antigens.
Decay-accelerating-factor (DAF, CD55), a phosphatidyl-inositol anchored glycoprotein, is a member of the cell membrane bound complement regulatory proteins that inhibit autologous complement cascade activation.
Serum-resistant B. burgdorferi strains bind complement factor H (FH) and FH-like protein 1 (FHL-1) on the spirochaete surface.
Native CRASP-3 and CRASP-5 also bind complement regulator CFHR1 and both isoforms of CFHR1 and CFHR2.
More recently, eculizumab, a monoclonal antibody which binds complement C5 and blocks terminal complement activation, has been developed.
Neutrophils express on their cell surfaces both complement receptors that bind complement-opsonized bacteria and Fc receptors that bind the Fc region of antibody-coated bacteria.
RBC possess adhesion molecules that bind complement fragments [ 29] and are therefore important for capturing and delivering such complexes to the reticuloendothelial system for elimination from circulation.
AnxA2 expressed on apoptotic cells themselves binds complement factors as signal for cell-cell interaction and phagocytosis (Leffler et al., 2010; Martin et al., 2012).
Of note, blebs can also bind complement, with a complement deficiency allowing these structures to escape into the periphery to induce responses as well as promote immune system and vascular changes.
Among a variety of Mtb receptors in the membrane of PMN, CD11b is one of the main receptor of phagocytosis which binds complement factor C3bi, as well as non-opsonized bacteria at a different site from C3bi binding site [ 38].
This small (77 amino acid) GPI-anchored cell-surface receptor binds complement components C8 and C9 (Ninomiya and Sims, 1992) and directly inhibits the formation of the membrane attack complex (MAC), an immune pore that kills microbes by the disruption of lipid bilayers.
