Veterinary Immunology and Serology

FUNCTIONS OF COMPLEMENT

• During activation of complements, several components are produced and each has distinct roles.
  • Opsonization and phagocytosis: Complement coated (C_3b or C_4b ) microbe are phagocytosed by binding to specific receptors on macrophages and neutrophils.
  • Complement mediated cytolysis: Cause lysis of foreign organisms mediated by the MAC and osmotic lysis . 
  • Responsible for removal of immune complexes
  • Activates the B cells and provides a signal for initiating humoral immune responses.
  • Anaphylaxis: Complement fragments C_3a, C_4a, and C_5a bind to mast cells and induce degranulation with the release of vasoreactive substances like histamine. These three peptides are also called anaphylatoxins as they trigger the mast cell reactions and cause anaphylaxis.