C-reactive protein

  • OMIM: 123260
  • UniProt: P02741
  • MGI: 88512

As C -reactive protein ( CRP) is referred to a protein that belongs to the family of pentraxins. CRP is produced in the liver and released into the blood. Together with ceruloplasmin, fibrinogen, haptoglobin, ferritin and other CRP is one of the acute-phase proteins. These are proteins in the blood, increase their blood concentrations during inflammatory ( infectious and non-infectious ) diseases. The strongest stimulus of the acute phase reaction thereby form bacterial infections.

The CRP is used as a non-specific inflammatory parameters, among others, to assess the severity of inflammatory diseases. Basically, the CRP concentration in plasma following disease activity, with a delay of 12-24 hours.

CRP is part of the immune system. It is an opsonin, which can activate the complement system. The expression of CRP in the liver is stimulated most strongly by interleukin 6 (IL -6).

In 2003, CRP plasma levels were recommended by the U.S. CDC as an additional marker for cardiovascular disease in otherwise healthy patients. A direct association with atherosclerosis could not be shown. Thus, a context is not considered during inflammatory diseases, which can cause much higher CRP levels.

Discovery and naming

CRP was first described in 1930 by William S. Tillett and Thomas Francis Jr. as a substance in the serum of patients with acute inflammation, with the C- polysaccharide ( C- teichonsäurehaltige substance) of pneumococcal reacts and causes together with calcium ion precipitation.

Mechanism of action

CRP binds phosphorylcholine, which is found on the surface of dead or dying cells ( and some types of bacteria). The bound CRP activates the complement, binds to macrophages and sets humoral and cellular effector mechanisms of the innate immune system in transition. This non-specific defense mechanism is significantly faster than the response of the specific immune system.

Reference range

CRP is present in healthy human blood. As normal values ​​apply to adults up to 10 mg / l (milligrams per liter) or 1 mg / dl (milligrams per deciliter ). There are also other laboratory normal values ​​, depending on the method of analysis.

Indication for determining

In recent years, high sensitivity tests to slightly elevated CRP levels to be used to recognize unstable phases in the context of atherosclerosis.

Determination methods and serum values

The determination of CRP in medical analysis can be carried out in various ways.

  • Visual latex agglutination test ( qualitative)
  • Fast immunodiffusion (semi- quantitative)
  • ELISA ( quantitative)
  • High-sensitivity CRP assay ( hs- CRP), this can low levels of CRP in serum (limit range: 0.04 mg / l) provide means of laser nephelometry in less than 30 minutes.

The CRP concentration in the serum of healthy individuals is normally less than 10 mg / l; with aging is observed a slight increase. Higher concentrations are found in women in late pregnancy, mild inflammation and viral infections (10-40 mg / l), in acute bacterial inflammation ( 40-200 mg / l), severe bacterial infections and burns ( > 200 mg / l ).

The extent of the CRP increase may give an indication of the severity of a disease:

  • Values ​​between 10 and 50 mg / l: Light or local ( localized ) inflammation. Furthermore, CRP may be slightly increased in smokers or endurance athletes.
  • 50 mg / l: severe inflammation
  • Over 100 mg / l: severe diseases, bacterial infections (blood poisoning (sepsis ), bacterial meningitis or pneumonia, complicated pancreatitis (pancreatitis ) ), major surgery, severe rheumatic disease in active stage, active Crohn's disease, some extensive tumors, severe acute osteomyelitis

Even in milder inflammatory processes may CRP increase slightly. Compared to another acute phase protein, the procalcitonin, CRP is more sensitive. CRP can therefore be used to track the progression of a disease.

In infections with viruses, the CRP concentration is hardly increased. Unlike bacteria, a virus has no own metabolic apparatus. Therefore, it penetrates into the body's own cells which are then manufactured the viral proteins. However, the complement system attacks only cells, which is untypical for the human membrane components wear ( such as bacteria ), and those which possess the adaptive immune system (antibodies) were recognized as foreign. Consequently, the CRP concentration increases with bacterial infections and organ transplantation (in the context of rejection ) - but rarely in viral infections.

According to a study by the University of Münster, there should be a correlation between elevated CRP levels and forgetfulness.

Protein isoform Human Genome Organisation Mouse Genome Informatics Euteleostomi Phagocyte Digital Object Identifier
157390
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