Increased activity in the biliary Con A-binding fraction accounts for the difference in crystallization behavior in bile from Chilean gallstone patients compared with Dutch gallstone patients.

Chile has one of the highest prevalences of cholesterol gallstone disease in the world. Recent data indicate that this is partly caused by genetic (Indian) factors. However, the causal factors inducing increased gallstone formation have not been elucidated. The aim of this study was to compare biliary composition and cholesterol crystallization in bile from patients of high and moderate risk areas (Chile and The Netherlands) for gallstone disease. Bile was sampled at cholecystectomy from 30 Chilean and 26 Dutch gallstone patients. The Con A-binding fraction (CABF) was extracted from fresh native bile samples by incubation with Con A-sepharose. Reconstitution of the CABF to the Con A-extracted native bile induced almost full recovery of crystallization confirming the validity of this technique. There was no difference between the two groups regarding sex and age. Chilean bile nucleated significantly faster (3.5 +/- 0.6 vs. 7.9 +/- 1.5 days) despite the fact that Dutch bile had a significantly higher cholesterol saturation index (CSI) (1.6 vs. 1.2, P = .01). The total lipid content was not different. Chilean bile contained more total protein (5 vs. 2.9 mg/mL, P = .008). IgG, IgM, Haptoglobin and alpha-1-acid glycoprotein were not different between the two groups. IgA, though, was significantly higher in the Chilean samples (0.44 vs. 0.19 mg/mL, P < .001). Extraction of CABF increased crystal observation time (COT) and decreased crystal growth in both groups. However, the effects were much more pronounced in the Chilean samples. Compared with Dutch bile, Chilean bile crystallizes much faster despite a lower CSI. Chilean bile contains an increased content of Con A-binding nucleation promoting activity.