Antigenic homology of feline and human beta-hexosaminidase

The immunological characteristics of feline beta-hexosaminidase (beta-D-N-acetylglucosaminidase, EC 3.2.1.30) isoenzymes, Hex A and Hex B, were studied. Immunization of rabbits and goats with either cat Hex A or Hex B produced antibodies which reacted with a common antigenic marker shared by both Hex A and Hex B. With properly absorbed antisera, a unique antigenic marker was demonstrated on cat Hex A, but not on Hex B. This antigenic profile is comparable to that of the human beta-hexosaminidase isozymes, in which both Hex A and Hex B share the antigenic determinant, beta, while only Hex A possesses the antigenic determinant, alpha. Ho cross-reactivity between the two species could be demonstrated using goat or rabbit antisera to either feline of human beta-hexosaminidase. These immunological data validate feline Gm2 gangliosidosis as a model for human Gm2 gangliosidosis type II, and facilitate the investigation of enzyme replacement therapy.