Construction And Immune Evaluation Of The Dendritic Cell Vaccine Pulsed With HPV16 L1

High-risk HPVs are closely associated with many malignant diseases.Accumulating evidence suggests that preventing HPV infection or clearing the HPV infected cells at early stage can effectively reduce the incidence of HPV-related malignancies.Currently,the prophylactic vaccines based on HPV L1 VLPs have been commercially available in United States and Europe,which can induce high titer of neutralizing antibodies in sera,but the therapeutic effects are poor.Due to their sustaining expression,the majority preclinical studies of therapeutic vaccine mainly focus on the HPV oncogenes E6/E7.Mounting evidence shows that the different level of HPV L1 antigens can be detect in HPV infected cells and HPV-positive tumor cells,which provides the rationale for the development of the novel therapeutic vaccines based on HPV L1.Known as the most powerful antigen-presenting cell,Dendritic cell(DC)has many unique functions such as antigen uptake,process and presentation,maintaining the immune homeostasis and immune response regulation.At present,many phase I/II clinical trials evaluating the antitumor effects of DC vaccines have been conducted,and some of them showed promosing results.Tumor immunotherapy is a comprehensive process which combined a variety of treatment measures,the single intervention only has limited effects.Our lab’s previous study evaluated the anti-tumor effects of different types of vector vaccines by sequential repeat immune strategy,the results showed that sequential immunized multi-vector vaccines can induce more potent and sustained cellular immunity and anti-tumor effects.Due to the important roles in immune regulation,in present study,we preliminarily evaluated the immunogenecity of DC pulsed with HPV16 L1(DC-L1)in order to further enhance the antitumor effect of multi-vector vaccines,which will lay the experimental foundation for the further combined application using DC-L1 and multi-vector vaccines.First,we obtained mature DCs derived from precursor cells in C57BL/6 mouse bone marrow(BM)and pulsed with HPV16 L1 antigen to construct DC vaccine DC-L1.The single-and triple-immunization were performed using DC-L1 vaccine and adenovirus vector vaccine Ad5-HPV16 L1,respectively.The HPV16 L1 specific cellular,humoral immune response and antitumor effects were evaluated respectively by ELISPOT,ELISA,in vitro killing experiment and tumor challenge assay.Our results showed that high-quality DC-L1 vaccine can be obtained by classical cytokine induce protocol with a minor optimisation in culture procesure.DC-L1 can induce L1-specific humoral and cellular immune responses.Compared with single-immunization,the triple-immunization of DC-L1 significantly enhanced the specific cellular immunity,and in line with this,the antitumor effect was also superior to the DC-L1 single-immunization;In other hand,there was no significant difference in specific humoral immune response between single-and triple-immunization.The results suggested that DC-L1 vaccine can effectively induce the L1 specific immune response by prime-boost-boost regimen and can be used combinedly with multi-vector vaccines.