Ｃ‐反応性蛋白（ＣＲＰ）のリガンド結合性のクロマトグラフィー的検討

Abstract

Human C-reactive protein (CRP), a typical acute-phase protein, increases about hundreds-fold in concentration in response to infection, inflammation or tissue injury.CRP was first described by Tillet and Francis in 1930 as a serum protein capable of precipitating pneumococcal C-polysaccharide where phosphorylcholine (PC) was identified later to be a ligand. Clinical and biological aspects, especially immunological ones, of human CRP have been studied. And some of them have been ascribed to its capacity of ligand-binding with PC calcium-dependently. While type 4 pneumococcal polysaccharide which lacks phosphate and choline has been pointed out to be able to bind human CRP in calcium-dependent manner, ligands other than PC should be considered besides PC.We find specific affinity chromatography bearing new ligand of negatively-charged aminocaproic acid which binds human CRP calcium-dependently (buffer ; 0.15 M NaCl, 0.02 M Tris, 0.01 M CaCl2, 0.01 M NaN3, pH 7.8, room temp.), being almost comparable to PC-affinity chromatography. In addition, another specific ligand of positively-charged aminohexyl-agarose is found to bind human CRP calcium-independently (buffer; 0.09 M NaCl, 0.01 M Tris, pH 7.4, room temp.) . These new ligands may provide simple model to understand human CRP.1) Tillet, W.S., Francis, T. Jr.: Serological reactions in pneumonia with a non-protein somatic fraction of pneumococcus. J. Exp. Med. 52: 561-571, 1930.2) Volanakis, J.E., Kaplan, M.H.: Specificity of C-reactive protein for choline phosphate residues of pneumococcal C-polysaccharide. Proc. Soc. Exp. Biol. Med. 136: 612-614, 1971.3) Kaplan, M.H., Volanakis, J.E.: Interaction of C-reactive protein complexes with the complement system. I. Consumption of human complement associated with the reaction of C-reactive protein with pneumococcal C-polysaccharide and with the choline phosphatides, lecithin and sphingomyelin. J. Immunol. 112: 2135-2147, 1974.4) Heidelberger, M., Gotschlich, E. C., Higginbotham, J.D.: Inhibition experiments with pneumococcal C and depyruvylated type-IV polysaccharides. Carbohyd. Res. 22: 1-4, 1972.5) Richards, R.L., Gewurz, H., Osmand, A.P., Alving, C.R.: Interactions of C-reactive protein and complement with liposomes. Proc. Natl. Acad. Sci. USA 74: 5672-5676, 1977.6) Volanakis, J.E., Wirtz, K.W.A.: Interaction of C-reactive protein with artificial phosphatidylcholine bilayers. Nature 281: 155-157, 1979.7) Narkates, A.J., Volanakis, J.E.: C-reactive protein binding specificities : Artificial and natural phospholipid bilayers. Ann. N.Y. Acad. Sci. 389: 172-182, 1982.8) Kushner, I., Kaplan, M.H.: Studies of acute phase protein. I. An immunohistochemical method for the localization of Cx-reactive protein in rabbits. Association with necrosis in local inflammatory lesions. J. Exp. Med. 114: 961-973, 1961.9) Kushner, I., Rakita, L., Kaplan, M.H.: Studies of acute-phase protein. II. Localization of Cx-reactive protein in heart in induced myocardial infarction in rabbits. J. Clin. Invest. 42: 286-292, 1963.10) Shephard, E.G., Van Helden, PD., Strauss, M., Bohm, L., De Beer, F.C.: Functional effects of CRP binding to nuclei. Immunol. 58: 489-494, 1986.11) Whisler, R.L., Newhouse, Y.G., Mortensen, R.F.: C-reactive protein reduces the promotion of human B-cell colony formation by autoreactive T4 cells and T-cell proliferation during the autologous mixed-lymphocyte reaction. Cell Immunol. 102: 287-298, 1986.12) Kilpatrick, J.M., Virella, G.: Inhibition of platelet-activating factor by rabbit C-reactive protein. Clin. Immunol. Immunophathol. 37: 276-281, 1985.13) Tatsumi, N., Hashimoto, K., Okuda, K., Kyougoku, T.: Neutrophil chemiluminescence induced by platelet activating factor and suppressed by C-reactive protein. Clin. Chim. Acta 172: 85-92, 1988.