beta-hexosaminidase in cultured normal and mutant human fibroblasts: an immunohistochemical and biochemical investigation.

Fibroblasts from a genetically normal individual and mutant fibroblasts from patients with Tay-Sachs and Sandhoff's diseases were grown in vitro. The lysosomal enzyme beta-hexosaminidase (Hex) was determined biochemically and localized with monoclonal antibodies recognizing Hex A, and Hex A and Hex B, respectively. The biochemical results showed similar amounts of Hex A and Hex B in the normal fibroblasts, whereas only Hex B activity was detectable in the fibroblasts from the patient with Tay-Sachs disease. The fibroblasts from the patient with Sandhoff's disease showed small amounts of Hex A- and no Hex B activity. Immunohistochemically, Hex was detectable with both antibodies in the normal fibroblasts and in those from the patient with Tay-Sachs disease. The fibroblasts from the patient with Sandhoff's disease were reactive only with Hex A-specific antibody.