Application of immunoglobulin allotyping in forensic stain analysis: reliability and sensitivity of Gm and Km typing

The detection of immunoglobulin alloantigens in bloodstains was studied. Commercially available allotyping reagents are suited for immunoglobulin allotyping in forensic bloodstain identification. The value and reliability of immunoglobulin allotyping in blood-stain extracts is greatly enhanced by testing for a wide scope of different allotypes. Particular reference is made to the application of a sensitive semiquantitative IgG estimation in relation to the detectability of the respective allotypes. The relative performance of the individual antigens in serum and extracts of fresh and aged bloodstains were obtained. On the basis of these results it was often possible to interpret negative reactions of the bloodstain extract in the hemagglutination-inhibition method with confidence. There is no evidence for the preferential loss of any of the alloantigens after drying and after aging of the blood.