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 i n the world. Recent data indicate that this is partly caused by genetic (In dian) factors. However, the causal factors inducing increased gallstone for mation have not been elucidated. The aim of this study was to compare bilia ry composition and cholesterol crystallization in bile from patients of hig h and moderate risk areas (Chile and The Netherlands) for gallstone disease . Bile was sampled at cholecystectomy from 30 Chilean and 26 Dutch gallston e patients. The Con A-binding fraction (CABF) was extracted from fresh nati ve bile samples by incubation with Con A-sepharose. Reconstitution of the C ABF to the Con A-extracted native bile induced almost full recovery of crys tallization confirming the validity of this technique. There was no differe nce between the two groups regarding sex and age. Chilean bile nucleated si gnificantly 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 b ile contained more total protein (5 vs. 2.9 mg/mL, P = .008), IgG, IgM, Hap toglobin 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 effect s were much more pronounced in the Chilean samples. Compared with Dutch bil e, Chilean bile crystallizes much faster despite a lower CSI. Chilean bile contains an increased content of Con A-binding nucleation promoting activit y.