Can keratin 8 and 17 immunohistochemistry be of diagnostic value in cervical cytology? A feasibility study

BACKGROUND. Based on results from evaluation of tissue sections from premal ignant lesions of the uterine cenix, the authors examined the hypothesis th at immunostaining of Papanicolaou-stained cytologic smears with monoclonal antibodies to keratins 8 and 17 allows detection of cervical intraepithelia l neoplasia (CIN) with progressive potential. They also investigated whethe r detection of these two keratin subtypes could be of help in the analysis of normal and/or poor quality cytology smears. METHODS. Sixty-one Papanicolaou-stained smears, representing 25 normal smea rs, 8 CIN 1, 7 CIN 2, 18 CIN 3, and 3 cervical carcinomas, were stained wit h CAM 5.2 and E3, which are capable of detecting keratin 8 and 17, respecti vely. The percent ages of immunoreactive normal, metaplastic, dysplastic, a nd malignant epithelial cells were determined. RESULTS. In normal cervical smears, keratin 8 was detected in endocervical columnar cells and sporadically in immature squamous metaplastic cells. Ker atin 17 was identified in reserve cells and frequently in immature squamous metaplasic cells. In GIN, the number of cases in which keratin 8 was prese nt increased with the severity of the lesion. Keratin 17 was found in the m ajority of CIN lesions, irrespective of grade. Intensity of immunostaining and number of cells stained per lesion varied and were also not related to the severity of GIN. CONCLUSIONS, The use of the keratin 8 antibody in normal cervical smears en abled the detection of endocervical cells in cases where they were thought to be absent, particularly in cases with severe inflammation. Staining with keratin 17 enabled the identification of reserve cells or immature metapla stic cells, which were often misinterpreted as parabasal cells. The applica tion of antibodies to these subtypes of keratins in cervical cytology can t o a certain extent help in the identification of CIN and may in future be t ested in automated screening. (C) 1999 American Cancer Society.