Correlation of immunochemical detection of HPV L1 capsid protein in Pap smears with regression of high-risk HPV positive mild/moderate dysplasia

OBJECTIVE: To immunostain Pap smears of high-risk (hr) HPV DNA-positive early squamous lesions for detecting HPV L1 protein. STUDY DESIGN: Routinely stained archival slides from 84 mild and moderate hrHPV DNA-positive dys-plasias were immunostained using a panreactive HPV L1 antibody. Follow-up smears were taken from women with remission for a mean period of 22.8 months (range, 6-46). Conization was done in patients with persistence or progression (3 and 48 patients, respectively) after a mean time of 12 months (range, 9-48). RESULTS: Twenty-nine of 84 smears (34.5%) had positively stained squamous epithelial cell nuclei. In 9 of 29 (31%) women progressive disease occurred (2 cervical intraepithelial neoplasia [CIN] 2 and 7 CIN 3 lesions on conization) 20 (69%) had remission. Of the 55 L1-negative cases, 13 (23.6%) had remission, 42 (76.4%) progressed (3 CIN 2, 38 CIN 3, 1 microinvasive carcinoma). The difference in follow-up between L1 positive and negative cases was statistically significant (x(2) test, Pless than or equal to 0.001). CONCLUSION: Low and moderate dysplastic squamous lesions without immunochemically detectable HPV L1 protein are significantly more likely to progress than are L1-positive cases. Immunochemical L1 capsid detection in routine Pap smears thus offers prognostic information about early dysplastic lesions.