Immunocytochemical detection of S-phase cells in normal and neoplastic cervical epithelium by anti-BrdU monoclonal antibody.

The use of a monoclonal antibody (MAb) to bromodeoxyuridine (BrdU) to identify S-phase cells was examined in 30 cervical biopsy specimens and 30 cervical smears from 18 patients with cervical neoplasia. Each patient received a local injection of 300 mg to 500 mg of BrdU into the cervix, at the time of endocervical laser conization, to label S-phase cells in neoplastic tissue. Labeled cells in normal and neoplastic tissues were detected in biopsy specimens or smears by indirect immunoperoxidase staining using the anti-BrdU MAb. The BrdU labeling index (BrdU LI, defined as the percentage of labeled cells in relation to the total number of cells counted) was calculated for all specimens. The level of BrdU-positive cells was 5.1% in normal cervical squamous epithelium, 12.3% in slight-to-moderate dysplasia and 21.2% in severe dysplasia to carcinoma in situ. In tissues without any dysplasia, BrdU-positive cells were mainly confined to the parabasal layer of the epithelium. In tissues showing slight-to-moderate dysplasia, BrdU-positive cells were mainly found in the lower half of the epithelium. BrdU-positive cells in severe dysplasia to carcinoma in situ were distributed throughout the full thickness of the epithelium. In addition, the few samples of squamous metaplasia and reserve cell hyperplasia encountered in this study exhibited a higher BrdU LI than did normal squamous epithelium. In cytologic specimens, BrdU-positive cells were found only in the cases of carcinoma in situ and in two cases containing normal cervical columnar epithelial cells. These results suggest that the immunocytochemical detection of BrdU by MAb staining may be useful for evaluating the proliferative activity in normal and neoplastic cervical epithelium.