[Immunoenzyme demonstration of isoantigens A, B and H in kidney tissue changed by putrefaction].

In contrast to blood serology, which usually fails in specimens more than a few days old, immunohistochemistry (PAP technique) provided reliable information on the blood group (ABO) and, in most cases, also the secretor character of 23 kidney specimens stored for months at room temperature. Better results were obtained with monoclonal antibodies than with human sera. In the late stages of decomposition, blood group diagnosis is based on the more decomposition-resistant antigens of the collecting tubular epithelium (in secretors) and the endothelia of the arteriolae medullares rectae and not on the identification of erythrocytic antigens. In addition, a decomposition-resistant epithelial antigen in the distal convoluted tubules (Tc II) is unmasked by autolysis or heterolysis. "Blood group" antigens were frequently detected in bacteria and fungi. These antigens, however, were clearly distinguishable from blood group characters of the tissue. A transient, weak, false-positive reaction with monoclonal anti-B appeared in decomposed Tc II epithelia.