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Cross-reacting material in Gaucher disease fibroblasts
Abstract:
Glucocerebrosidase is the enzyme that is deficient in Gaucher diseases. Four monoclonal antibodies reacting with at least two different epitopes of this enzyme have been produced. The amounts of glucocerebrosidase in fibroblasts of patients with all three types of Gaucher disease were investigated by radioiodinating two of the antibodies and measuring their binding to fibroblast extracts immobilized on nitrocellulose filters. The amount of glucocerebrosidase antigen was decreased in all cases of Gaucher disease, particularly in the fibroblasts of patients with the more severe neuronopathic forms of the disorder, types II and III. The catalytic activity was reduced to a greater extent than the amount of antigen in all cases, so that the specific activity of the residual enzyme was found to be diminished. Although measurements in individual cases were quite reproducible and the amount of antigen detected by monoclonal antibodies reacting with different epitopes was quite similar, there was considerable variation between patients. This finding is consistent with the apparent within-type genetic heterogeneity of Gaucher disease, even within the Ashkenazi Jewish population in which it is most prevalent.
Insights
Gaucher disease patients show reduced glucocerebrosidase enzyme levels and activity. This study quanties the enzyme deficiency using monoclonal antibodies in Gaucher disease fibroblasts.
Area of Science:
- Biochemistry
- Genetics
- Immunology
Background:
- Gaucher disease is a lysosomal storage disorder caused by deficiency of the enzyme glucocerebrosidase.
- Understanding the molecular basis of Gaucher disease is crucial for developing effective therapies.
Purpose of the Study:
- To quantify the amount of glucocerebrosidase antigen in fibroblasts from patients with all three types of Gaucher disease.
- To investigate the relationship between glucocerebrosidase antigen levels and enzyme activity.
Main Methods:
- Production of four monoclonal antibodies against glucocerebrosidase, recognizing at least two distinct epitopes.
- Radioiodination of two monoclonal antibodies for quantifying glucocerebrosidase antigen.
- Measurement of antibody binding to fibroblast extracts immobilized on nitrocellulose filters.
Main Results:
- Glucocerebrosidase antigen levels were decreased in all Gaucher disease patients, with greater reductions in severe neuronopathic types (II and III).
- Enzyme catalytic activity was reduced more significantly than antigen levels, indicating diminished specific activity of the residual enzyme.
- Significant variation in antigen levels was observed among patients, even within the same disease type.
Conclusions:
- Monoclonal antibodies are effective tools for quantifying glucocerebrosidase antigen in Gaucher disease.
- The study confirms reduced enzyme levels and activity in Gaucher disease fibroblasts.
- Observed patient variability supports the concept of genetic heterogeneity within Gaucher disease subtypes.