Characterization of feline blood group antigens

Feline blood group antigens are of clinical importance in veterinary medicine due to their role in hemolytic transfusion reactions in cats and neonatal isoerythrolysis in kittens. The objectives of this project were to produce and characterize monoclonal antibodies specific for the feline erythrocyte A and B antigens, and to use these antibodies to further investigate the expression of the A and B antigens on erythrocytes of blood type A, B and AB cats.;Three murine IgM monoclonal antibodies, two specific for feline blood type A erythrocytes and one specific for blood type B erythrocytes were produced. Specificities of each were characterized by tube agglutination tests, high performance thin layer chromatography immunostaining of feline erythrocyte membrane glycolipids, and by immunoblotting of feline erythrocyte membrane proteins separated by SDS-PAGE. Each anti-A monoclonal antibody specifically agglutinated all type A samples and agglutinated some, but not all, type AB samples. One anti-A monoclonal antibody detected the disialoganglioside N-glycolylneuraminic acid, the major glycolipid antigen of type A erythrocytes. The other anti-A monoclonal antibody detected a glycolipid that may be a trisialoganglioside form of N-glycolylneuraminic acid. The anti-B monoclonal antibody specifically agglutinated erythrocytes from all type B cats and 9 of 10 type AB cats. This antibody detected the disialoganglioside N-acetylneuraminic acid, the major glycolipid antigen of type B erythrocytes. None of the monoclonal antibodies recognized erythrocyte membrane glycoproteins specific for either feline type A or B erythrocytes.;The monoclonal antibodies were used to characterize the feline AB phenotype. Flow cytometry immunostaining of erythrocytes from four type AB cats with each of the anti-A monoclonal antibodies demonstrated variable reactivity between erythrocytes of different type AB cats. Each anti-A monoclonal antibody bound 100% of type A erythrocytes. One of these antibodies bound 2.5 to 4% of erythrocytes from three type AB cats, and 61% of erythrocytes from the other type AB cat. The second anti-A monoclonal antibody bound 20--38% of erythrocytes from the same three type AB cats, and 68% of erythrocytes from the other type AB cat. Tube agglutination scores were comparable to the amount of binding detected by flow cytometry. Thin layer chromatography immunostains confirmed differences in the amount of A antigen between erythrocyte glycolipids of type A and AB cats and of two different type AB cats. These results demonstrate that there are at least two phenotypes within the feline AB blood type that differ in the amount of expression of A antigen on the erythrocyte surface.