[Serum antibodies in dogs with autoimmune disorders recognize 40 kd glycoprotein in the nucleus of mammalian cells].

We report a new antibody specificity in 15 sera recovered from a group of dogs developing systemic lupus erythematosus (SLE) or clinically related disorders. This antibody stains in a speckled fashion the nucleus of human Hep-2 cells. Immunodiffusion tests with saline extracts of rabbit thymus showed that all 15 sera generate a common precipitation line which crosses the lines from reference sera to Sm, SS-A/ro, SS-B/La, and RNP antigens. The target nuclear antigen is a 40 kD polypeptide (p40). An important property of p40 resides in its ability to bind specifically Wheat Germ Agglutinin lectin but not Concanavalin A, supporting the notion that the antigen is a glycoprotein bearing a N-acetylglucosamine moiety.