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 PC 10). 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 (mm²) 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 (l.6 ± 1.23) and radicular (l.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.