Vaccine against human papillomavirus (HPV)-associated lesions induces collaboration between natural killer and dendritic cells in vitro.

Cervical cancer, the second most frequent gynaecological malignancy in the world, is caused by infection with high-risk human papillomaviruses (HPV). HPV16 and/or 18 are detected in more than 70% of these tumours. Prophylactic HPV-L1 virus like particle (VLP) vaccines are highly efficient to protect against HPV16 and HPV18 infection, but not against established infection. In this context, we study the effect of HPV-VLP on natural killer cells (NK) and on the crosstalk between NK and Dendritic Cells (DC).
In order to know if HPV-VLP are able to enter in NK cells, we used fluorescent HPV-VLP with flow cytometry and confocal microscopy. HPV-VLP were internalised more rapidly in NK cells than in DC. They were already detected inside NK cells after 10 min of contact at 37°C. We also observed in CD107 assays, that HPV-VLP induce degranulation of NK cytotoxic granules.
Previous works have shown that HPV-VLP were able to activate DC. We confirmed these results and observed an increase of CD69 cell surface expression and IFN-γ production by NK cells in the presence of DC activated by VLP. Interestingly, NK cells seemed to further activate DC in the presence of VLP as shown by an up-regulation of HLA-DR and CD86 on DC. Moreover, NK cells in the presence of HPV-VLP induced the production of IL12p70, but not the immunosuppressive cytokine IL10.
Our results suggest that NK cells could play a role in the activation of DC induced by HPV-VLP during the vaccination against cervical cancer.
Supported by the Belgian FNRS-Télévie