beta-Glucosidase isoenzymes in Epstein-Barr virus-transformed lymphoid cell lines from normal subjects and patients with type 1 Gaucher disease.

Lymphoid cell lines (LCL) from 3 adult patients with non-neuropathic Gaucher disease were established by Epstein-Barr virus (EBV) transformation and were investigated from the view of enzymology. Glucosylceramide-beta-glucosidase (GlcCer-beta-glucosidase) was present in soluble and particulate fraction of LCL from normal subjects and was deficient in type 1 Gaucher LCL; the deficiency of all molecular forms, shown by electrofocusing, indicates that they are coded by the same gene. The existence of two non-specific beta-glucosidases, one soluble (minor), the other membrane-bound (major), was demonstrated in leucocytes and LCL from normals; in Gaucher LCL, these were also present in a normal range. Characteristic properties of the non-specific membrane-bound beta-glucosidase were defined: lability at acidic pH and strong inhibitory effect by detergents. These properties allowed to discriminate it from the lysosomal GlcCer-beta-glucosidase and to define optimal assay conditions for determination of residual GlcCer-beta-glucosidase activity in Gaucher disease, using artificial substrate, without interference of non-specific membrane-bound beta-glucosidase. These results demonstrate that EBV-transformed LCL represent an accurate model system for enzymatic studies of Gaucher disease.