CRP is useful, for example, in: |
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- distinguishing bacterial infections from viral infections
- monitoring the course of an illness
- monitoring and controlling postoperative infections
- following up the efficacy of antimicrobial therapy
- predicting future cardiovascular diseases.
CRP is a cyclic pentameric serum protein with a relative molecular mass of approximately 120 kD (Fig. 1).
It has five identical noncovalently bound subunits each composed of 206 amino acids. It is synthesised in
the liver and epithelial cells upon stimulation by inflammatory lymphokines (interleukin-6, interleukin-1,
tumour necrosis factor). The gene sequence for human CRP was cloned in 1985. CRP belongs to the pentraxin
protein family of oligomeric calcium-bindingproteins.
CRP was discovered in 1930 by Tillet and Francis who observed that the sera of some acutely ill patients
precipitated the capsular C polysaccharide of Streptococcus pneumoniae. The serum factor causing
precipitation was later identified as a protein and designated as C-reactive protein (CRP).
CRP is part of a nonspecific immune defence mechanism which is able to bind pneumococcal
capsular C polysaccharide, phosphocholine groups of membrane residues as well as chromatin in the presence
of Ca++ ions. It is able to activate the classical complement pathway and function as
opsonin in leukocyte phagocytosis, lymphocyte stimulation or monocyte/macrophage activation.
CRP has also been detected in atherosclerotic plaques, mainly bound to partly degraded lowdensity lipoprotein.
CRP may also increase the production of tissue factor by macrophages.
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