Preparation of Monoclonal Antibodies Against Acid α-D-Glucosidase for Study of Chinese Glycogenosis Type II Patients

Two monoclonal antibodies (Mabs), 8-23 and 4-6, against human acid α-D—glucosidase were generated to analyse the intracellular α-D—glucosidase from seven Chinese Pompe's disease families with the following study design: [1] Purified α-D—glucosidase from normal human urine was used as antigen for immunization of mice. [2] The splenic cells of immunized mice were isolated and fused with myeloma cells NS-1 for generation of hybridomas and production of anti-human α-D—glucosidase Mabs and detection of presence of the enzyme in skin fibroblasts obtained from the Pompe's disease families and normal controls. [3] Functional assay of acid α-D—glucosidase was done. Both generated Mabs were IgGl with a κ light chain. Mabs 8-23 and 4-6 can recognize 70 kd (kilodaltons) α-D—glucosidase evidenced by radioimmunoprecipitation (RIP). Our results showed that α-D—glucosidase did exist in the skin fibroblasts of all seven Pompe's disease patients by RIP and in the hepatic cells by immunohistological study. However, functional assay of α-D—glucosidase of the seven patients with Pompe's disease showed that the enzyme function of α-D—glucosidase was defective. This finding is at variance with the results of other workers which indicated that the amount of mature enzyme was reduced or totally absent in most of the juvenile and adult Caucasian and South African patients. The discordance may imply that the cause of α-D—glucosidase deficiency in Chinese patients is quite different from that in Caucasian and South African patients. This needs further study to clarify.