A sensitive enzyme-linked immunosorbent assay used to differentiate type AB specimen from a mixture of type A and type B specimens.

A sensitive enzyme-linked immunosorbent assay (ELISA) for detection of ABO blood substances in human body fluids was devised. The ELISA plates coated with purified human anti-A or anti-B serum effectively captured the blood substances, and these were then analysed by the combination of rabbit anti-A and goat anti-B. This capture ELISA could differentiate the type AB specimen from a mixture of the type A and the type B specimens, and the method was applied to rape cases to make the ABO typing of the criminal.