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C-reactive protein (CRP) is a long-established marker that belongs to a family of proteins known as pentraxin. The conserved nature of this protein among the evolution of vertebrate indicates this protein plays important roles during immunologic responses. In addition, it considered that CRP can act as a unique acute phase protein that having a direct activity on complementary system to removal of pathogens. The production of CRP in liver occurs mainly in responding to activation of interleukin- 6 (IL-6), and there is a good association has been found between the level of IL-6 and CRP. The normal human CRP concentration ranged 0.8 mg / 1 and is <10 mg / L in normal state, and concentrations larger than this value is consider as abnormal indicating an existence of infection. Also, many conditions can change the concentrations of CRP involved tissue necrosis, burns, trauma, surgery, inflammatory diseases that mediated immunologically, cancer and crystal-induced inflammatory diseases. There are 2 conformational isoforms of CRP including pentameric (pCRPs) and monomeric (mCRP) which having variable biological and antigenic electrophoretic properties. pCRP is a permanent form found in sera and is appeared as a very stable molecule, but the current evidences suggested that this form can be dissociated to mCRP in both in vivo and in vitro. The high expression of mCRP have demonstrated in diabetic plaque lesion concerning to the extensive systemic inflammations. Site for binding of CRP to phosphatidylcholine locates on lateral surface and requires binding for 2 Ca ions at a particular hydrophilic pockets called the Ca-dependent ligand binding. Recent reports have shown the ability of CRP to bind to LOX-1 receptor to induce the modification vascular responses to vasodilator, infiltration of leukocyte and activation of complement system.