Comparison of CEA distribution in lesions and tumors of salivary glands as determined with monoclonal and polyclonal antibodies

Application of immunohistochemistry to the diagnosis of salivary gland tumors

A panel of antibodies composed of the cytokeratins (CKs), vimentin, and actin was applied to 114 minor salivary gland tumors to evaluate its diagnostic value. The results revealed that luminal cells of intercalated duct-like structures, such as those seen in pleomorphic adenoma, basal cell adenoma, adenoid cystic carcinoma, and epithelial-myoepithelial carcinoma, expressed CKs 7, 8, 14, and 19. The outer cells of these structures exhibited vimentin or vimentin plus muscle-specific actin, but rarely CK14, which is seen particularly in pleomorphic adenoma, in the tubular type of basal cell adenoma, and seldom in the tubular type of adenoid cystic carcinoma. Modified myoepithelial cells of pleomorphic adenoma and myoepithelioma exhibited a variable immunoprofile. CKs 7 and 8 were also observed in acinar cell adenocarcinoma and polymorphous low-grade adenocarcinoma with vimentin in the latter. CK13 was expressed only by canalicular adenoma and mucoepidermoid carcinoma cells. This study showed that the panel of antibodies employed is effective in distinguishing among salivary gland tumors.

Myoepithelium of salivary glands

In salivary glands and other exocrine organs, there are starfish-shaped cells that lie between the basal lamina and the acinar and ductal cells. These have structural features of both epithelium and smooth muscle cells, and so are called myoepithelial cells. Their functions include contraction when the gland is stimulated to secrete, compressing or reinforcing the underlying parenchymal cells, thus aiding in the expulsion of saliva and preventing damage to the other cells. They also may aid in the propagation of secretory and other stimuli. Their common developmental origin with the basal cells of the larger ducts is displayed in the mature glands by shared structural and immunohistochemical features, but most such basal cells do not have the distinguishing features of myoepithelial cells, such as myofibrils. Although myoepithelial cells can be identified by light microscopy through enzyme histochemistry and special stains and immunohistochemistry for their myofibrils, these techniques can be misleading in salivary gland neoplasms. Thus, the most reliable means of identifying neoplastic myoepithelial cells is with a combination of histochemistry and electron microscopy. The extent to which these cells are derived from undifferentiated stem cells in both normal and neoplastic growth is controversial. The presentation here of transmission electron microscopy (TEM) of well-differentiated myoepithelial cells in mitotic division indicates that stem cells are not necessarily the only source of myoepithelial cells in the later stages of salivary gland development or in neoplasia.

Colloid cyst of the third ventricle. A comparative immunohistochemical study of neuraxis cysts and choroid plexus epithelium

In an effort to shed light upon the nature of the colloid cyst, the immunohistochemical properties of 21 examples of this lesion were compared with those of other neuraxial cysts and choroid plexus epithelium. The neuraxial cysts included the following: eight Rathke's cleft cysts, 25 pituitaries containing follicular cysts of the pars intermedia, and four enterogenous cysts. Fifteen examples of normal choroid plexus and 12 choroid plexus papillomas were studied as well. These lesions were examined for localization of the following antigens: cytokeratins, epithelial membrane antigen, secretory component, carcinoembryonic antigen, prealbumin, vimentin, glial fibrillary acidic protein (GFAP), S-100 protein, neuron-specific enolase, 68-kD neurofilament protein, chromogranin, serotonin, and lysozyme, and with Leu-7 monoclonal antibodies. Five colloid cysts were immunostained with monoclonal antibodies that were specific for Clara-cell antigens and surfactant, respectively. Sugar moieties were localized using Ulex europaeus I, and Ricinus communis agglutinin I lectins. All Rathke's cleft cysts and follicular cysts of the pars intermedia as well as three selected colloid cysts were examined for pituitary hormones. The epithelial cells of colloid and enterogenous cysts, as well as those lining follicular and Rathke's cleft cyst, showed uniformly strong reactivity for cytokeratins, epithelial membrane antigen, secretory component, and vimentin, and bound Ulex europaeus lectin. Occasional cells in colloid cysts were positive for Clara cell-specific antigens. Reaction for carcinoembryonic antigen was present on the apical surface of scattered cells of colloid, follicular, and Rathke's cleft cysts. Many cells of follicles in the pars intermedia as well as individual cells of five Rathke's cleft cysts were also immunoreactive for chromogranin, S-100 protein, GFAP, and pituitary hormones. Colloid and enterogenous cysts were negative for prealbumin, S-100 protein, GFAP, and neuron-specific enolase; in all but a few instances, they failed to bind Ricinus communis agglutinin. In contrast, normal choroid plexus and choroid plexus papillomas were positive for prealbumin, S-100 protein, neuron-specific enolase, cytokeratin, vimentin, and Ricinus communis agglutinin receptors; they lacked Ulex europaeus lectin, 56/66-kD cytokeratins, and epithelial membrane antigen. Unlike normal choroid plexus, choroid plexus papillomas were often GFAP-positive. All tissues studied were nonreactive for lysosome, serotonin, and neurofilament, and with Leu-7 antibodies. This study indicates that the immunophenotype of epithelium lining colloid cysts is similar to that of other cysts showing endodermal or ectodermal differentiation and to respiratory tract mucosa. Epithelium of colloid cysts is immunohistochemically different from that of normal or neoplastic choroid plexus. These findings indicate an endodermal rather than neuroepithelial nature for colloid cysts.

Immunohistochemical localization of MAM-3 and MAM-6 antigens in adenoid cystic carcinoma

MAM-3 and MAM-6 antigens were detected immunohistochemically in 34 cases of adenoid cystic carcinomas (ACC) of the salivary glands and these patterns were compared to these of epithelial membrane antigen (EMA) and laminin. ACC was histologically divided into three types; the cribriform pattern, the tubular and trabecular pattern, and the solid cluster pattern. Immunostaining of EMA and MAM-6 antigen had a similar distributions in the luminal borders of luminal tumor cells, whereas the MAM-3 antigen was slight or negative in luminal borders. Myoepithelial derived tumor cells of ACC accompanying hyaline stroma demonstrated positive staining for the MAM-6 antigen (whole cell positive type), and luminal tumor cells of microcysts showed strong staining for the MAM-3 antigen. Laminin staining was confined to the basement membrane and surface borders in pseudocyst cavities. In salivary gland ACC, laminin staining can be used as a marker of pseudocyst surfaces and immunostaining of EMA and the MAM-6 antigen as a marker of luminal borders of cyst. These two histochemical markers were useful for discriminating pseudocyst and cyst.

Immunohistochemical localization of carcinoembryonic antigen (CEA) in salivary gland tumors

Carcinoembryonic antigen (CEA) was first isolated from colonic carcinoma and has been used as a diagnostic marker. CEA has also been observed in a variety of epithelial tumors and normal tissues. In this study, CEA was localized by means of immunohistochemical procedures in benign and malignant salivary gland tumors, as well as in normal parotid gland, indicating that CEA is not a reliable marker for differentiation between benign and malignant salivary gland neoplasms.

Multiple expression of tissue markers in mucoepidermoid carcinomas and acinic cell carcinomas of the salivary glands

The distribution of various tissue antigens was studied in mucoepidermoid carcinomas (n = 74) and acinic cell carcinomas (n = 38) by means of immunocytochemistry. Mucoepidermoid carcinomas were generally positive for cytokeratin and showed double expression for cytokeratin and vimentin in 31.1% and triple expression for cytokeratin, vimentin and GFAP in 24.1%. CEA was studied using new monoclonal antibodies which distinguish between epitopes that are present on CEA alone and those which are present on nonspecific cross reacting antigens as well. The monospecific CEA antibody was completely negative in mucoepidermoid carcinomas, while nonspecific cross reacting antigens (NCAs) were positive in mucoepidermoid carcinomas to a varying degree. Alpha 1-antichymotrypsin, a marker formerly thought to be specific for tissues for histiocytic origin, was positive in 85.1% of mucoepidermoid carcinomas. Twenty three percent of mucoepidermoid carcinomas showed focal infiltration by S-100 positive dendritic stromal cells, tumour cell being negative. Leu-M1 antigen was positive in 58.1% of mucoepidermoid carcinomas. Acinic cell carcinomas were generally positive for cytokeratin and in single cases showed double expression for cytokeratin and vimentin and triple expression for cytokeratin, vimentin and GFAP. Monospecific CEA antibody positivity could be demonstrated in 24.2% of acinic cell carcinoma, while nonspecific cross reacting antigens (NCAs) were positive in acinic cell carcinomas to a varying degree. Alpha 1-antichymotrypsin was positive in 97.4% of acinic cell carcinomas. 2.5% of acinic cell carcinomas showed focal infiltration by S-100 positive dendritic stromal cells, 2.5% of acinic cell carcinomas were positive for S-100 protein with no dendritic stromal cells present. Leu-M1 antigen was positive in 86.8% of acinic cell carcinomas. For S-100 protein and Leu-M1, no correlation with the clinical course, as reported previously for other tumours, could be observed.

Immunohistochemical expression of MAM-3 and MAM-6 antigens in salivary gland tumours

MAM-3 and MAM-6 antigens of human milk fat globule membrane were detected immunohistochemically in 93 cases of salivary gland tumours as well as in normal glands. The antigens were visualized in 10% formalin-fixed paraffin sections. MAM-3 (MoAbs 115G3, 67D11) antigen was distributed in intercalated and striated duct cells of the normal salivary glands, and in luminal tumour cells and squamous metaplastic cells of pleomorphic adenomas. In pleomorphic adenomas the frequency of positive staining with MoAb 67D11 (54/67; 80.6%) was higher than that with MoAb 115G3 (36/67; 53.7%). MAM-6 (MoAbs 115D8, 115F5) antigen was expressed in luminal and lateral borders of serous acinar cells and ductal of the normal glands, and also in luminal borders of tubulo-ductal and glandular structures of salivary gland tumours. Ductal basal cells were characterized by existence of positive staining for MAM-6 antigen, in adenolymphomas MAM-6 antigen was restricted to the basal tumour cells. Some mucous cells of mucoepidermoid tumours were stained specifically with MoAb 115G3, and epidermoid cells of mucoepidermoid carcinomas manifested MAM-6 antigen staining. Immunohistochemical localization of MAM-6 antigen resembled that of epithelial membrane antigen (EMA) detected with MoAb.

Epithelial membrane antigen as a marker of human salivary gland acinar and ductal cell function

Monoclonal antibody to epithelial membrane antigen (EMA) from human milk fat globule membrane was used with the immunoperoxidase method to examine the distribution of EMA in normal human salivary glands and in their obstructive lesions. EMA staining in the normal salivary gland was limited to luminal and lateral borders of acinar cells. The antigen was also present in high concentration on the luminal side of ductal cells. In obstructive lesions or sialoadenitis, lateral border and luminal positive staining in atrophic acinar cells was reduced or absent, and the EMA staining in duct-like structures was also markedly decreased on even absent in chronic stage. The degree of reduction in EMA staining was dependent on the extent of degeneration. Expression of immunohistochemically detectable EMA in paraffin sections suggests the antigen to be useful as a new marker of salivary gland function, of either acinar compartments or ductal segments.