COMPLEMENT SYSTEM
COMPLEMENT SYSTEM
- Complement system is a part of the immune system that helps or complements the ability of antibodies and phagocytic cells to clear pathogens from an organism. It is part of the immune system, which is not adaptable and does not change over the course of an individuals life time.
- The complement system consists of a number of small proteins found in the blood, in general synthesised by the liver, and normally circulating as in active precursors.
- When stimulated by several triggers proteases in the system cleave specific proteins to release cytokines and initiate an amplifying cascade of further cleavages.
- The end result of this is massive amplifications and activation of the cell killing membrane attack complex.
- Over 30 proteins and protein fragments make up the complement system.
- They account for about 5% of globulin fraction of blood serum and can serve as opsonins.
FUNCTIONS OF COMPLEMENT
SYSTEM
- The biological activities of this system affect both innate and adaptive immunity and reach far beyond antibody-mediated lysis of bacteria and red blood cells.
- After initial activation, the various complement components interact, in a highly regulated cascade, to carry out a number of basic functions.
- Lysis of cells, bacteria, and viruses
- Opsonization, which promotes phagocytosis of particulate antigens
- Binding to specific complement receptors on cells of the immune system, triggering specific cell functions, inflammation, and secretion of immunoregulatory molecules.
- Immune clearance, which removes immune complexes from the circulation and deposits them in the spleen and liver
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