Immunoperoxidase Technics in Diagnostic Pathology: Report of a Workshop Sponsored by the National Cancer Institute

The use of immunoperoxidase technics has spread dramatically in recent years to almost daily use in certain clinical and surgical pathology laboratories. A wide variety of cell products, including enzymes, polypeptide and steroid hormones, immunoglobulins, oncodevelopmental antigens, viral antigens, and other cell-specific proteins, have been demonstrated in frozen or conventionally fixed and embedded tissue sections by the use of these methods. Major applications of these technics at present include demonstration of various immunoglobulin classes in tumors of lymphoreticular origin and atypical lymphoproliferative processes, identification of polypeptide hormones in endocrine tumors, and demonstration of various tumor markers such as carcinoembryonic antigen and alpha fetoprotein in neoplastic and preneoplastic conditions. The indirect peroxidase conjugate and peroxidase antiperoxidase procedures are presented and reviewed in detail with emphasis on tissue preparative procedures, evaluation of tissue and immunologic controls, background staining, and evaluation of results. The danger of false-negative and false-positive results should be dealt with in a precise manner so that results from different laboratories are both reliable and reproducible. The application of immunoperoxidase technics represents a major advance for the surgical pathologist, but additional evaluation, development, and standardization are required. To accomplish this, comparative studies of the same material, including known positive and negative tissue controls, by different laboratories should be encouraged.