PARAFFIN IMMUNOHISTOCHEMICAL DETECTION OF CD56, A USEFUL MARKER FOR NEURAL CELL-ADHESION MOLECULE (NCAM), IN NORMAL AND NEOPLASTIC FIXED TISSUES

CD56, the neural cell adhesion molecule (NCAM), is a natural killer (N K) cell-associated antigen that has been identified as a neuroendocrin e marker. CD56 is present in carcinoid tumors, paragangliomas, and neu roendocrine carcinomas, and may be seen in nonneuroendocrine carcinoma s, myeloid leukemias, some T cell lymphomas, and multiple myeloma. To date, most studies detecting this antigen have been performed on fresh or frozen tissue. We applied either of two monoclonal CD56 antibodies to routinely-fixed, paraffin-embedded sections of various normal (aut opsy) tissues and tumors using the avidin-biotin-peroxidase complex me thod with an automated immunostainer. We found optimal reactivity of C D56 using microwave-based epitope retrieval, as reactivity was markedl y decreased with enzymatic pretreatment. Autopsy tissues showed strong marking of peripheral nerve, adrenal zona glomerulosa and medulla, an d synapses in cerebral cortex. CD56 marked thyroid follicular epitheli um, proximal renal tubules, hepatocytes, gastric parietal cells, and p ancreatic islet cells. Merkel cell carcinoma, neuroblastoma, gangliogl ioma, oligodendroglioma, glioblastoma multiforme, pheochromocytoma, re tinoblastoma, laryngeal and pulmonary squamous cell carcinomas, pulmon ary and intestinal carcinoids, pulmonary small-cell undifferentiated c arcinoma, pancreatic islet cell tumor, hepatocellular carcinoma, renal cell carcinoma, follicular and papillary thyroid carcinoma, NK cell l ymphoma and NK-like T-cell lymphoma marked positively. We conclude tha t CD56 can be detected in paraffin-embedded tissues following nonenzym atic epitope retrieval in some normal tissues, tumors of neuroendocrin e origin, and other neoplasms known to express NCAM.