Induction of antigen-specific immunity by pH-sensitive carbonate apatite as a potent vaccine carrier

The ability of carbonate apatite (CO3Ap) to enhance antigen-specific immunity was examined in vitro and in vivo to investigate its utility as a vaccine carrier. Murine bone marrow-derived dendritic cells took up ovalbumin (OVA) containing CO3Ap more effectively than free OVA. Interestingly, mice immunized with OVA-containing CO3Ap produced OVA-specific antibodies more effectively than mice immunized with free OVA. Furthermore, immunization of C57BL/6 mice with OVA-containing CO3Ap induced the proliferation and antigen-specific production of IFN-γ by splenocytes more strongly than immunization with free OVA. Moreover, no significant differences were detected in the induction of delayed-type hypersensitivity responses, an immune reaction involving an antigen-specific, cell-mediated immune response between OVA-containing CO3Ap and OVA-containing alumina salt (Alum), suggesting that CO3Ap induced cell-mediated immune response to the same degree as Alum, which is commonly used for clinical applications. This study is the first to demonstrate the induction of antigen-specific immune responses in vivo by CO3Ap.

► To develop effective vaccine, we examined the effects of CO3Ap as an antigen carrier.
► OVA contained in CO3Ap was taken up by BMDCs more effectively than free OVA.
► OVA-immunized splenocytes was activated by OVA contained in CO3Ap effectively.
► OVA contained in CO3Ap induced strong OVA-specific immune responses to C57BL/6 mice.
► CO3Ap is promising antigen carrier for the achievement of effective vaccine.