They can activate leukocytosis and the complement, cause protease inhibition, lead to clotting and
opsonisation -a defense mechanism that lead to the elimination of infectious agents, tissue repair and restoration of the healthy state (CRAY et al., 2009).
It is thought that these defects lie in the serum complement factors leading to component 3B (C3B)/inactive component 3B (iC3b)
opsonisation or its receptor.2
Association of low levels of mannan-binding protein with a common defect of
opsonisation, Lancet, 1989,.
Heterophils mediate
opsonisation during phagocytosis [38].
This way, they have the possibility of a very easy way to build an interaction with an antigen-antibody complex, which will stimulate immediate reactivity of macrophage to
opsonisation. Then, peptide expression will follow on the superficial membrane cell through the major histocompatability complex I (MHC I), and then induce cell-mediated immune response through an endogenous process (Kehry and Castle, 1994).
When immunoglobulins cover the antigen, a series of different reactions can occur including complement activation and pathogen
opsonisation in order to neutralize and evacuate pathogens.
However, they have also been shown to have a protective function via downregulation of inflammation and the
opsonisation of myelin debris which facilitates clearance by phagocytic cells [127, 128].
aureus produces an important cell wall surface protein A (spa) which impairs the process of
opsonisation and phagocytosis by binding with immunoglobulin G (Gao and Stewart, 2004).
At the same time, complement proteins coat the surface of pathogens, signalling and providing receptor binding sites for professional phagocytes to attach--a process called
opsonisation. Fragments of complement proteins produced during the chemical cascade act as signals for further immune responses.
Surface
opsonisation promotes the removal of particles from the circulation within seconds to minutes through the mononuclear phagocytic system (MPS), also known as reticuloendothelial system (RES), and by Kupffer cells, phagocytic macrophages permanently located in the liver [4].
The complement system is one of the main players of the innate immune system, and its activation results in pathogen
opsonisation, production of anaphylotoxins (which recruit cells to the site of infection), phagocytosis, and lysis.
