title: Demonstration of cross-reacting material in Tay-Sachs disease.
abstract: Antibodies against placental hexosaminidase A and kidney alpha-subunits were raised in rabbits after cross-linking the antigens with glutaraldehyde. Anti-(alpha(n)-subunit) antiserum (anti-alpha(n)) precipitated hexosaminidase A but not hexosaminidase B, whereas anti-(hexosaminidase A) antiserum precipitated both hexosaminidases A and B. Specific anti-(hexosaminidase A) antiserum was prepared by absorbing antiserum with hexosaminidase B. Both anti-alpha(n) and anti-(hexosaminidase A) antisera precipitated the CR (cross-reacting) material from eight unrelated patients with Tay-Sachs disease. Immunotitration, immunoelectrophoresis, double-immunodiffusion and radial-immunodiffusion techniques were used to demonstrate the presence of CR material. The CR-material-antibody complex was enzymically inactive. Antiserum raised against kidney or placental hexosaminidase A, without cross-linking with glutaraldehyde, failed to precipitate the CR material, implying that treatment of the protein with glutaraldehyde exposes antigenic determinants that are hidden in the native protein. Since anti-(hexosaminidase B) antiserum did not precipitate the CR material during the immunoelectrophoresis of Tay-Sachs liver extracts, it is suggested that altered alpha-subunits do not combine with beta-subunits. By using immunotitration we have demonstrated the competition between the hexosaminidase B-free Tay-Sachs liver extract and hexosaminidase A for the common binding sites on monospecific anti-(cross-linked hexosaminidase A) antiserum. The amount of CR material in the liver samples from seven cases of Tay-Sachs desease was found to be in the same range as theoretically calculated alpha-subunits in normal liver samples. Similar results were obtained by the radial-immunodiffusion studies. The present studies therefore suggest that Tay-Sachs disease is caused by a structural-gene mutation.
mesh_terms: D000941:Antigens / Q000276:immunology*; D003429:Cross Reactions; D000939:Epitopes; D005796:Genes; D006596:Hexosaminidases / Q000276:immunology*; D006801:Humans; D007106:Immune Sera; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007527:Isoenzymes / Q000276:immunology*; D008099:Liver / Q000276:immunology; D013661:Tay-Sachs Disease / Q000201:enzymology / Q000235:genetics / Q000276:immunology
chemical_list: D000941:Antigens; D000939:Epitopes; D007106:Immune Sera; D007527:Isoenzymes; D006596:Hexosaminidases