A simple and sensitive method for the determination of blood group antigens in secretions.

A simple method for the determination of ABH blood group antigens in secretions has been developed. Blood group ABH specific monoclonal antibodies were covalently bound to blue dyed microspheres of acryl polymer with a diameter of 2.2 microns. The dyed microspheres coated with anti-A, -B and -H antibodies were found to be agglutinated specifically on a plastic microtiter plate by the corresponding blood group antigens secreted in saliva. The agglutination reactions with saliva samples were also observed rapidly and conveniently in a glass capillary tube which contained the same antibody immobilized dyed microspheres. The procedure provides a simple and sensitive method for the determination of blood group antigens through the visible agglutination reaction of dyed microspheres despite the invisibility of the antigens.