Individual proteins – proteins of the acute phase – types, analytical methods for investigation, indications for investigation, patient preparation, reference ranges, results interpretation.
Acute-phase proteins (APPs) are a class of proteins whose plasma concentrations increase (positive acute-phase proteins) or decrease (negative acute-phase proteins) in response to inflammation. This response is called the acute-phase reaction. Examples Positive reactants includes: C-reactive protein, Antitrypsin, fibrinogen, ceruloplasmin, serum amyloid A and haptoglobin. Example of negative reactants includes prealbumin, albumin, and transferrin
C-reactive protein (CRP) is a protein found in the blood, the levels of which rise in response to inflammation. CRP is a member of the class of acute-phase reactants, as its levels rise dramatically during inflammatory processes occurring in the body. This increment is due to a rise in the plasma concentration of IL-6, which is produced predominantly by macrophages as well as adipocytes. CRP binds to phosphocholine on microbes. It is thought to assist in complement binding to foreign and damaged cells and enhances phagocytosis by macrophages (opsonin mediated phagocytosis), which express a receptor for CRP. The C-reactive protein medical test measures levels of CRP to assess acute inflammation. It is also believed to play another important role in innate immunity, as an early defence system against infections. Arterial damage results from white blood cell invasion and inflammation within the wall. CRP is a general marker for inflammation and infection, so it can be used as a very rough proxy for heart disease risk. Blood, usually collected in a serum- separating tube, is analysed in a medical laboratory or at the point of care.
Analytical methods for investigation:
Various analytical methods are available for CRP determination, such as ELISA, immunoturbidimetry, rapid immunodiffusion, and visual agglutination. A high-sensitivity CRP (hs-CRP) test measures low levels of CRP using laser nephelometry.
Reference ranges: up to 3 mg/l.