Characterization of Monocyte-Derived Dendritic Cells able to induce an E6/E7-specific, HLA I-restricted, cytotoxic activity

The adoptive transfer of cancer Ag-specific effector T cells in patients can result in tumor rejection, thereby illustrating the immune system potential for cancer therapy. Viruses involved in tumorigenesis are useful targets because viral proteins are not expressed in normal cells and their expression is required to maintain the malignant phenotype. Between oncoviruses, high risk human papillomavirus (HPV) has a well-characterized transforming propriety and it has been associated with squamous cell carcinoma of the ano-genital and oral tracts. Cutaneous genotypes are, instead, associated with some forms of non-melanoma skin cancer. Transforming ability of HPV is based on the function of E6 and E7 viral oncoproteins, which interact and inactivate pRB and p53 oncosuppressors, respectively. For these reasons vaccines targeting oncogenic E6 and E7 are ideal candidates to elicit strong immune responses without generating autoimmunity. Here we report results obtained using a protocol based on human monocyte-derived dendritic cells (MDDC) and/or langerhans cells (MDLC) incubated in vitro with necrotic keratinocytes expressing both E6 and E7 oncoproteins derived from mucosal (HPV16) or cutaneous (HPV38) genotypes. We observed the capability of MDDCs i) to uptake necrotic material from transformed keratinocytes; ii) to upregulate the expression of class I HLA and CD86 co-stimulatory molecule following uptake and iii) to specifically prime in vitro cytotoxic T lymphocytes against E6/E7-expressing keratinocytes. We also provide preliminary evidences indicating the ability of necrotic keratinocytes to alter the microRNA profile in immature MDLC compared to prototipical stimuli as bacterial lipopolisaccharyde.