Analysis of IgG reactivity against Human Papillomavirus type-16 E7 in patients with cervical intraepithelial neoplasia indicates an association with clearance of viral infection: results of a prospective study

IgG reactivity against the immunodominant region aa6-35 of Human Papillomavirus (HPV) type-16 E7 was determined in a peptide-based ELISA in a cohort study of women with initial mild to moderate cervical dyskaryosis. On the basis of HPV DNA patterns, as determined by PCR in cervical smears prior to IgG testing, HPV-16-positive patients were grouped as having either a cleared, a fluctuating, or a persistent HPV-16 infection. In a cross-sectional study at the start of serological follow-up, positive IgG reactivities were found more often in the total group of HPV-16-positive patients (20.0%) than in patients consistently typed as HPV-negative over a period of at least 12 months prior to testing (3.1%, p < 0.04). The highest proportion of positive responders was found in patients with a cleared HPV-16 infection (29.4%). Also, IgG reactivities found in HPV-16 clearance patients were significantly higher than in patients with a persistent infection (p < 0.008). In a subsequent longitudinal study over a period of up to 27 months, consistently positive reactivities were observed in patients with cleared viral infections who showed seroreactivity in the cross-sectional study, while mostly negative reactivities were found in patients with viral persistence. HPV-16 E7-specific IgG subclass responses were determined in a selection of 19 CIN and 11 HPV-16-positive cervical carcinoma (CeCa) patients with positive E7-specific IgG responses. IgG2 was predominant in the CIN patients, suggesting the presence of IFNgamma (Th1) at the site of HPV infection. In the CeCa patients IgG1 and IgG2 were produced equally, possibly indicating a rise in Th2 cytokines. Our data suggest that HPV-16 E7 IgG reactivity in a subset of CIN patients with viral clearance may result from successful Th1 responses.