Any substance that promotes cellular phagocytosis.
Opsonization by humoral components:
- the mannose-binding protein, which binds
mannans and is recognized by the C1q receptor.
- the surfactant protein A, which binds
carbohydrates and is recognized by a transmembrane receptor, SPR210.
- complement proteins
fragment fixed non specifically to the carbohydrate surface of pathogens via
the alternative pathway, which is recognized by the C3bi receptors (CRs) on
macrophages (CR1, CR3, and CR4), responsible for particule internalization.
fixed to IgM that specifically recognizes epitopes on the surface of the
which recognize epitopes on infections agents and are recognized by the Fc
antibodies are much more effective opsonins than IgM antibodies in the absence
of complement, but IgM antibodies are more effective opsonins in the presence