Cytokeratin(CK) 13 protein expression in the epithelial linings of dentigerous cysts

Objective To investigate expression of CK13 when a metaplastic change occurs from ciliated columnar cells to squamous cells. Methods Fifty-four cases of dentigerous cysts and 6 cases of nasal cysts were immunohistochemically stained against CK13 monoclonal antibody. The expression of CK13-mRNA was examined by RT-PCR in 28 cases of cysts. Results All 54 cases of squamous cells expressed CK13. Eight cases of ciliated columnar cell epithelia in upper jaws expressed CK13 in some areas of the columnar cell epithelium, though very few. As shown by RT-PCR CK13-mRNA was expressed most strongly in squamous cell epithelium. The CK13-mRNA expression levels in the linings which consisted of both columnar cells and squamous cells were higher than those in linings of columnar cells only. Conclusion CK13-mRNA expresses in three different epithelial linings: ciliated columnar epithelium, mingled epithelium (containing both ciliated columnar cells and squamous cells) and striated squamous epithelium, but the expression was at different level from weak to strong. CK 13 was positive in metaplastic squamous cells, but negative in ciliated columnar cells. However, CK13 was expressed when squamous cell epithelium was found in ciliated columnar epithelium, CK 13 was expressed. Therefore, CK13 can be regarded as the marker of a metaplastic change from ciliated columnar cells to squamous cells. Yet, as an initial marker, it needs further examination.