Abstract: It has been known that blood group substances in body fluids from group AB individuals possess both group A and B activities on the same macromolecules. We applied the results of such studies to differ of group ABSe body fluids (or stains) from mixtures of group ASe and BSe body fluids (or stains) by a sensitive "Sandwich method" enzyme-linked immunosorbent assay (ELISA).The polystyrene ELISA plates were sensitized with monoclonal anti-A or anti-B. A or B substance fixed to plates was quantitatively analysed by the combined use of human anti-A or anti-B and horseradish peroxidase labeled anti-human IgM. The 10000 fold diluted body fluids could be detected by this method. In type AB body fluids, A and B substances were detected with monoclonal anti-A sensitized plate or anti-B sensitized plate. In the mixture of type A and type B body fluids: however, only type A or type B substances were detected with corresponding plate.

Key words: Forensic immunology, ABO blood group system, body fluids, ELISA, Monoclonal anti-A and anti-B