BINDING REACTIVITY OF C-REACTIVE PROTEIN FOR POLYCATIONS .2. MODULATORY EFFECTS OF CALCIUM AND PHOSPHOCHOLINE

Human C-reactive protein selectively and reversibly precipitates with certain small polymers of arginine and lysine. In this report, Ca was shown to inhibit this reactivity in a dose-dependent manner, in direct contrast to the requirement for Ca for precipitation of CRP with C-polysaccharide. In the presence of phosphocholine, CRP rapidly precipitated and formed stable complexes with the polycationic polymers in the otherwise inhibitory Ca concentrations. .alpha.-Glycerol-phosphocholine, unlike phosphocholine, did not reverse this inhibitory effect. These results extend the characterization of the binding reactivity of CRP for polycations and suggest a relationship between this binding site and the sites for Ca and phosphocholine. CRP-polycation interactions in the presence of phosphocholine may have physiologic significance during the acute inflammatory process.