Effects of phospholipase A2, free fatty acids and 2-lysolecithin on the crystallization of cholesterol in gallbladder bile

Background Phospholipase A2 (PLA2) and its enzymatic products free fatty acids (FFAs) and 2‐lysolecithin are physiological constituents of bile. Their role in the crystallization of cholesterol in gallbladder bile of patients with cholesterol gallstones is still controversial. Design To clarify this issue we evaluated the activity of PLA2 and the concentration and pattern of FFAs in the gallbladder bile of cholesterol stone patients. We furthermore added PLA2, FFAs and 2‐lysolecithin to isotropic gallbladder bile, determined the crystal observation time (COT) and counted the cholesterol crystals in a crystal growth assay for up to 21 days. Results A PLA2 activity of 1.8 ± 1.2 U L−1 and total FFA concentrations of 1.32 ± 0.71 mmol L−1 were determined. After incubation of bile for 24 h at 37 °C total FFAs increased to 2.72 ± 1.29 mmol L−1 (P