Endogenous phosphatase activity in tumor cells in a liver aspirate. A potential problem for immunocytodiagnosis using...

Immunocytochemical studies were performed on fine needle aspirates of the liver in a patient with hepatocellular carcinoma. A panel of commercially available antibodies was used to study the aspirated cells by immunoalkaline phosphatase and immunoperoxidase methods. The malignant cells in the aspirates, which were positively stained by the immunoperoxidase method for alphafetoprotein and by both methods for epithelial membrane antigen, were most probably hepatocellular in origin. Some cells were shown by the immunoalkaline phosphatase method to possess leukocyte-common antigen (LCA) and antigens of colonic and ovarian tissues. These findings were further investigated, and it was found that the tumor cells indeed had LCA as well as levamisole-resistant alkaline phosphatase activity. Although the immunoalkaline phosphatase methods are useful immunodiagnostic techniques applicable to fine needle aspirates, the endogenous enzyme activity present in some nonhematopoietic tumor cells is a cause for caution in the use of these methods in aspirates from nonhematopoietic tumor tissues.