The rapid determination of the ABO group from body fluids (or stains) by dot enzyme-linked immunosorbent assay (dot-ELISA) using enzyme-labeled monoclonal antibodies.

Using ABH enzyme-labeled monoclonal antibodies, the authors could rapidly detect the ABO group from body fluids and body fluid stains by the dot enzyme-linked immunosorbent assay (dot-ELISA). In this test, the antigen was immobilized on nitrocellulose paper; the entire piece of paper was coated with an appropriate dilution of enzyme-labeled McAb directly against the antigen of interest; and, finally, 3,3'-diaminobenzidine (DAB) substrate solution was added. The site of a positive reaction is clearly visible as a brown spot. We analyzed 521 samples and got satisfactory results. We also analyzed 99 practical case samples by this method and achieved the same results as those obtained by other researchers using other methods. This method is accurate, simple, direct, rapid, and sensitive; it also produces easily observed results, requires no equipment, and can be completed in 30 min. The test proved to be clearly more sensitive for the detection of the ABO blood group in secretor saliva than the conventional hemagglutination inhibition test. Also saliva diluted 10(-4) to 10(-5) and the ABO group of nonsecretor saliva and urine could be easily detected by this method.