C-Reactive Protein

C-reactive protein (CRP) is an acute-phase serum protein. It is a member of the pentraxin family, produced mostly by cells in the liver in response to a variety of inflammatory cytokines. The levels of CRP in the blood are closely associated with the degree of inflammatory responses. CRP levels rise rapidly in response to threats such as trauma, inflammation, and infection and fall rapidly in response to remission. Thus, CRP levels are considered as non-specific markers of inflammation, and measurement of CRP levels has important clinical significance for the diagnosis of some inflammatory diseases such as rheumatoid arthritis, lupus, and vasculitis.

CRP has been indicated a role in the innate immune system through activating complement, binding to Fc receptors, and acting as an opsonin for a variety of pathogens. CRP interacts with Fc receptors, leading to the production of pro-inflammatory cytokines that increase the inflammatory response. CRP binds to microbial polysaccharides or to the ligands exposed on damaged cells, leading to the activation of the classical complement pathway and promoting their uptake by phagocytic cells. Importantly, CRP also recognizes altered self and foreign molecules based on pattern recognition, inducing a proinflammatory signal and activating the adaptive immune system. Recent studies have also shown that CRP serves an important role in the inflammatory process, including phagocytosis, nitric oxide release, and cytokine production.

Fig.1 CRP is predominantly secreted from the liver and adipose tissue(s) in response to inflammatory stress resulting from plaque rupture and subsequent microembolization. (Schulz, 2011)

Reference

1. Schulz, R.; et al. C-Reactive Protein. Hypertension. 2011, 57(2):151-153.