Enzyme-linked immunosorbent assay for A and B water soluble blood group substances.

The conditions affecting an enzyme-linked immunosorbent assay for salivary blood group substances were investigated. It was found that A, B, and O secretor saliva samples would each bind both anti-A and anti-B typing reagents. The conditions that affected the assay response were optimized for maximum sensitivity and to give the highest resolution possible between the result for an antiserum binding to homologous antigen and the response for heterologous antigen-antibody combinations. Monoclonal antibodies eliminated the heterologous binding indicating that this binding was due to a lack of specificity of the routine typing reagents. A sensitive assay using the monoclonal antibodies to distinguish between samples of A and B secretor saliva is described.