QUANTIFICATION OF PCNA(+) CELLS WITHIN ODONTOGENIC JAW CYST EPITHELIUM

The aim of this study was to investigate the reactivity of the epithelial linings of the three major types of odontogenic cyst with a monoclonal antibody to proliferating cell nuclear antigen (PCNA; clone PC10). PCNA expression was studied in odontogenic cysts (n = 31) and normal oral epithelium (n = 10) using a biotin-streptavidin method on routinely processed paraffin sections. PCNA(+) cells were counted manually and related to the length of basement membrane (mm) and the epithelial area (mm(2)) as determined by TV image analysis. The epithelial linings of odontogenic keratocysts (OKC; n = 11) contained the highest number of PCNA(+) cells, most of which were located in the suprabasal layers. The mean value of PCNA(+) cells in OKC linings (94.4+/-22.7 cells/mm) was similar to that of oral epithelia (80.8+/-20.6 cells/mm), but both were significantly higher than that of dentigerous (n = 10, 5.1+/-3.0 cells/mm) and radicular (n = 10, 11.0+/-4.1 cells/mm) cyst linings (P < 0.005). The epithelial distribution of PCNA(+) cells differed between groups with the basal/suprabasal PCNA(+) cell ratio in OKC linings (0.05+/- 0.02) being significantly lower than that of normal oral epithelium (0.5+/-0.14), dentigerous (1.6+/-1.23) and radicular (1.9+/-1.09) cyst linings respectively (P < 0.005). These results demonstrate differences in PCNA expression between the epithelial linings of the major odontogenic cyst types, indicating differences in proliferative and differentiation processes within these lesions.