Purpose: To characterize HPV16 E6- and E7-specific T-cell immunity in patients with high-grade squamous intraepithelial lesions (HSIL).
Experimental design: Peripheral blood mononuclear cells isolated from 38 patients with HPV16+ HSIL were used to determine the magnitude, breadth, and polarization of HPV16-specific T-cell responses by proliferation assays and cytokine assays. Furthermore, HSIL-infiltrating T cells isolated from 7 cases were analyzed for the presence of HPV16 E6- and/or E7-specific T cells, phenotyped, and tested for the specific production of IFN-gamma and interleukin-10 as well as for their capacity to suppress immune responses.
Results: HPV16-specific T-cell responses were absent in the circulation of the majority (approximately 60%) of patients who visit the clinic for treatment of a HPV16+ HSIL lesion. Notably, HPV16-specific T-cell reactivity was predominantly detected in patients returning to the clinic for repetitive treatment of a persistent or recurrent HPV16+ HSIL lesion after initial destructive treatment. The majority (> 70%) of these HPV16-specific T-cell responses did not secrete proinflammatory cytokines, indicating that most of the subjects, although in principle able to mount a HPV16-specific immune response, fail to develop protective cellular immunity. This notion is sustained by our observation that only three HSIL-infiltrating T-cell cultures contained HPV16-specific T cells, one of which clearly consisted of HPV16 E7-specific regulatory T cells.
Conclusions: The presence of HPV16-specific T cells with a non-Th1/Th2 cytokine and even suppressive signature in patients with HSIL may affect the outcome of vaccine approaches aiming at reinforcing human papillomavirus-specific immunity to attack human papillomavirus-induced lesions.