IFN-γ produced by human papilloma virus-18 E6-specific CD4 + T cells predicts the clinical outcome after surgery in patients with high-grade cervical lesions

Cervical neoplastic lesions are associated with infection by high-risk human papilloma viruses (HPVs). HPV-16 and HPV-18 are the most common genotypes. It has been proposed that development of HPV-16-positive cervical lesions is associated with impaired CD4⁺ T cell immunity against early Ags. The aim of the study was to evaluate whether this impairment also applies to HPV-18. We investigated the presence and the quality of anti-HPV-18 E6 CD4⁺ T cell responses in the blood of 37 consecutive patients with high-grade cervical lesions, 25 normal donors, and 20 cord bloods. The immune infiltrate in the cervical lesions was also evaluated. The characteristics of the responses were correlated to the clinical outcome. We found that one or more HPV-18 E6 peptides, containing naturally processed epitopes, were able to induce a response in 40-50% of the patients, depending on the effector function tested. Importantly, these percentages rose to 80-100% when HPV-18-positive patients were considered. HPV-18 E6-specific CD4⁺ T cells produced mixed Th1/Th2 responses and statistical analysis of the cytokines produced revealed that the amount of IFN-γ released could predict infection persistence and/or disease relapse after surgery. Finally, we found that a higher number of infiltrating CD4⁺ and T-bet⁺ T cells in the lesions correlated with a favorable clinical outcome. Our results strongly suggest a relevant role for CD4⁺ T cells in the control of the HPV-18 compared with HPV-16 infections in patients with high-grade cervical lesions and identify an immunologic parameter potentially useful for patients' stratification.