PHOSPHOCHOLINE REVERSES INHIBITION OF PULMONARY SURFACTANT ADSORPTION CAUSED BY C-REACTIVE PROTEIN

The influence of the acute inflammatory phase protein human C-reactive protein (CRP) on the adsorption of porcine pulmonary surfactant from a subphase into an air-water interface has been investigated. CRP was shown to detract from the ability of surfactant to rapidly adsorb to the air-water interface at a molar ratio of 0.03:1 (protein:phospholipid) (weight ratio, 0.5:1). On a weight basis, CRP was found to be more effective than fibrinogen at reducing the adsorption rate of surfactant. The effect of CRP required the presence of calcium and was reversed by the addition of phosphocholine in a concentration-dependent manner. The inhibition of surfactant adsorption by CRP was effectively eliminated by the addition of phosphocholine at a molar ratio of 300:1 (phosphocholine:CRP), but it was not diminished by the addition of identical molar ratios of o-phosphoethanolamine or DL-alpha-glycerophosphate at the same molar ratios. These data suggest that the potent inhibition of surfactant adsorption by CRP is primarily a result of a specific interaction between CRP and the phosphocholine headgroup of surfactant lipids in the subphase and that it can be reversed by the water-soluble CRP ligand, phosphocholine.