[Immunocytochemical examination of biological traces on knife blades]

In cases of penetrating stab wounds by different knives it is highly relevant to prove which knife caused which injury, especially if one of the injuries was lethal. This is possible by immunocytochemical examination of cellular material remaining on the injuring blade because some organs have organ-specific antigen determinants such as alpha-l-fetoprotein in the liver cells or cardiac troponin I in the heart muscle cells, to which antibodies can bind. Even when penetrations occur through several layers of clothing, enough cells from the injured organ remain on the blade of a knife to allow immunohistochemical examination. These cells can be collected by means of adhesive film or wiping the blade and can be stained immunocytochemically. The organ specificity of the examined proteins allows proof of their origin. The present study shows that immunocytochemical alpha-l-fetoprotein and cardiac troponin I staining of the cells remaining on a knife blade enables proof of whether the knife blade injured the heart or the liver, or both.