Evidence for the deficiency of beta-glucosidase-activating factor in fibroblasts of patients with I-cell disease.

Reduced activity of beta-glucosidase was shown in the cultured skin fibroblasts of four patients with I-cell disease when the enzyme was tested without the use of detergents. In the presence of taurocholate and triton X100 beta-glucosidase activity was normal. This suggested a deficiency of a beta-glucosidase activating factor in I-cell fibroblasts rather than of the enzyme itself. The deficiency of beta-glucosidase activity was corrected to some extent by mixing cell lysates, and more effectively by cocultivation and fusion of I-cell disease and Gaucher fibroblasts. These results present evidence for the presence of a beta-glucosidase-activating factor in normal and Gaucher fibroblasts. In fibroblasts of patients with I-cell disease this activator is probably deficient, as is the case for most lysosomal enzymes.