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C3 component of complement in the blood

Alexey Portnov, medical expert
Last reviewed: 23.04.2024

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The reference values (norm) of the C3 content in the serum are 0.55-1.2 g / l.

C3 is the key complement component necessary for the realization of cytolysis. It is synthesized in the liver and is part of the resulting immune complexes. C3 is activated along the classical pathway by complexes of antigens with IgG, IgM, in an alternative way - complexes of Ar with IgA, IgE, Fab fragments of Ig, polysaccharide antigens of bacteria.

Reducing the concentration of the C3 component in the blood serum leads to a weakening of the opsonizing function of the blood, phagocytosis, cytolysis, and may be due to a violation of its synthesis or increased catabolism, as well as its adsorption on immune complexes in autoimmune (immunocomplex) diseases. An increase in serum C3 concentration is characteristic of the acute period of infection (the "acute phase" protein). In the period of convalescence, the C3 concentration is normalized.

Changes in C3 concentration for various diseases

Increase in concentration

Acute bacterial, fungal, parasitic and viral infections
Cholestasis
Cholelithiasis

Reduction in concentration

Congenital defects of complement, deficiency of complement system
Autoimmune diseases
Systemic lupus erythematosus
Glomerulonephritis
Recurrent infections
Raynaud's disease
Lymphogranulomatosis, chronic lymphocytic leukemia
Herpetiform dermatitis
Immunocomplex diseases
Hepatitis, cirrhosis of the liver
Treatment with cytostatics and immunosuppressants
Ionizing radiation

trusted-source [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]

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