Immunohistochemical distribution of monoclonal antibodies against keratin in papillomas and carcinomas from oral and nasopharyngeal regions.

Papillomas (40) and squamous cell carcinomas (75) were examined for the presence of three keratin proteins with the use of an immunohistochemical technique. Polyclonal keratin antibody (TK, detecting 41 to 65 kDa keratin) and monoclonal antibodies KL1 and PKK1 (55 to 57 kDa and 41 to 56 kDa, respectively) were used. Squamous epithelium in normal oral mucosa showed marked TK staining in cells of upper strata and relatively slight staining in basal layer cells, moderate KL1 staining in spinous and granular layers and was negative in basal cells. Positive PKK1 staining was noted in cells of the basal layer. Columnar epithelium in the nasal mucosa showed TK staining in all layers, KL1 staining on the apical side of epithelial cells and trace or negative staining in basal layer cells. There was moderate PKK1 staining along the apical side of cells and variable staining in basal cells. Keratin distribution in oral papillomas was similar to that in normal oral epithelium, whereas in nasal and nasopharyngeal papillomas, keratin distribution was restricted to the upper layers. Tonsillar papillomas showed a strong TK reaction, negative KL1 in upper layer cells, and marked PKK1 staining in basal cells. Well-keratinized squamous carcinomas indicated an irregular TK distribution and decreased KL1 and negative PKK1 stainings. Intermediate and poorly differentiated keratinizing squamous carcinoma showed irregular staining patterns for the three classes of keratins studied. Immunohistochemically detectable keratins utilizing monoclonal antibodies were described as useful markers of epithelial tumors of squamous origin. Keratin expression within benign tumors was related to normal regional distribution, whereas in malignant tumors, keratin distribution was irregular in its distribution profile.