Live attenuated SIV vaccines are not effective in a postexposure vaccination model

We examined the immunohistochemical expression of proliferating-cell nuclear antigen (PCNA) and p53 proteins in dysplasia and intramucosal carcinoma of the esophagus. Immunohistochemistry was performed with monoclonal antibodies directed against PCNA and p53. We used surgically resected specimens from 29 patients who had a total of 55 lesions of severe dysplasia (n = 16), intraepithelial carcinoma (n = 21), and mucosal carcinoma (n = 18). The mean PCNA index with immunoreactivity for p53 was 48.9 +/- 6.5 in areas of severe dysplasia (n = 7), 58.2 +/- 7.3 in areas of intraepithelial carcinoma (n = 10), and 71.4 +/- 9.3 in the invasive areas of mucosal carcinoma (n = 10). The mean PCNA index without immunoreactivity for p53 was 41.2 +/- 5.5 in areas of severe dysplasia (n = 9), 48.0 +/- 7.4 in areas of intraepithelial carcinoma (n = 11), and 63.7 +/- 9.1 in invasive areas of mucosal carcinoma (n = 8). The PCNA indices of the areas of severe dysplasia with immunoreactivity for p53 were significantly lower than those of intraepithelial carcinoma and mucosal carcinoma with immunoreactivity for p53. Similarly, the PCNA indices of severe dysplasia without immunoreactivity for p53 were significantly lower than those of intraepithelial carcinoma and mucosal carcinoma without immunoreactivity for p53. These results thus suggest that severe dysplasia has a lower proliferative potential than carcinoma and may therefore represent a precancerous lesion.