opsonization

Opsonins bind to target antigens, marking their carrier for phagocytosis. Opsonin molecules include IgG antibodies and components of the complement system (C3b, C4b, and iC3b).

Phagocytic cells express opsonin-binding receptors, and opsonization promotes phagocytosis in addition to inducing increasing the expression of complement receptors on phagocytes.