Involvements of fibronectin and lysophosphatidylcholine for selective binding of C-reactive protein

C-reactive protein (CRP) has been reported to deposit only to inflammatory sites, but not to normal sites. In present paper, we investigated involvements of fibronectin and lysophosphatidylcholine (lyso-PC) as responsible for this selectivity. In ELISA assay, CRP was found to bind to immobilized fibronectin with dose dependency, only in the presence of Ca2+ ions. Addition of 5 mM EDTA allowed CRP to abolish this binding. However, it could not be inhibited neither by phosphorylcholine nor by heparin. On the other hand, CRP could aggregate liposome consisted of lyso-PC and phosphatidylcholine (PC), but not that consisted of PC alone. Aggregation was found to be maximum when liposome with lyso-PC/PC molar ratio of 0.3 was used. Similar result was also observed in binding study with peroxidase-labelled CRP. In addition, phospholipase A2 treatment of liposome consisted of PC alone induced 3-fold higher binding than that found with untreated one. Ca2+ ions were required for binding to liposome.