Main pentraxins (C-reactive protein, CRP, and serum amyloid P component, SAP) are acute phase proteins preserved during evolution from Limulus polyphemus to man. Classical short pentraxins are multimeric proteins composed of variable numbers of non-covalently associated subunits. Human CRP is a pentamer, as is generally the case in members of the family. SAP is composed of two pentameric disks interacting face-to-face. CRP and SAP are made in the liver in response to inflammatory mediators, most prominently interleukin-6. As cytokine-inducible acute phase protein, CRP concentrations in the blood increase dramatically upon infection or trauma. A number of ligands, recognized in a calcium-dependent manner, have been identified for CRP and SAP, including DNA and chromatin, immune complexes, various sugars, and complement components. Moreover, SAP binds with all forms of amyloid fibrils and, in addition, to fibronectin, C4-binding protein, and glycosami- noglycans. Pentraxins represent a mechanism of innate resistance against microbes, tools to scavenge cellular debris and components of the extracellular matrix as illustrated by amyloid deposits. CRP and SAP are associated with many pathological lesions, including the amyloid deposits and neurofibrillary tangles of Alzheimer disease. Since its discovery in 1930, CRP has been studied as a screening device for inflammation, a marker for disease activity, and as a diagnostic adjunct. Improved methods of CRP quantifying have led to increased application in clinical medicine.

        Key words: C-reactive protein, hepatocyte, interleukin-6, pentraxins, serum amyloid A.