Applicability of an immuno-microsphere technique for a forensic identification of ABO blood types: the use of fluorescent microspheres.

In order to develop a direct micro-method for the ABO blood typing of forensic samples, an attempt has been made to utilize fluorescent immuno-microspheres. Microspheres (Covaspheres MX and CX particles, Duke Scientific) were coupled with partially purified antibodies from commercial mouse monoclonal anti-A, anti-B, and anti-H reagents, as well as with affinity purified UEA-I. The reactivity and specificity of the immuno-microspheres were checked with fresh erythrocytes of known blood groups, after which the spheres then were applied to the typing of hemolyzed and thermo-changed erythrocytes and bloodstains. The microspheres coated with the monoclonal antibodies and the UEA-I showed specific and distinct reactions with fresh, hemolyzed and thermo-changed erythrocytes, and bloodstains. Further, by combining particles labelled with different dyes, the possibility of a simultaneous double-labelling of the group antigens was indicated on the fresh cells and on the hemolyzed and thermo-changed cells and cell fragments.