C3 component of complement in the blood
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
[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]