In vitro Assay for Screening of Optimal Targets for Antigen-Delivery to Murine Dendritic Cells

Targeting of antigen to dendritic cells (DCs) increase the efficiency of immunization procedures and may facilitate the development of more effective vaccines. Several surface molecules on DCs have shown to be useful for antigen targeting, but many more deserves investigation for their efficacy in this respect. With this end in mind, a simple in vitro assay for screening of optimal targets for antigen-delivery to murine DCs was established. Splenocytes from mice immunized with rat IgG were targeted in vitro with a panel of different rat monoclonal antibodies (mAbs) directed against surface markers on murine DCs. The resulting T-cell activation was analysed by determining the number of IFN-γ and IL-4 secreting cells by ELISPOT. A positive effect of targeting was evident with several of the mAbs. Thus, mAbs against CD11c, CD36, CD205 and Clec7A all induced IFN-γ responses that were significantly higher than those induced by non-targeting control mAbs. Anti-CD36 also induced IL-4 responses that were significantly higher than the control. The assay described here allows simultaneous analysis of a large number of potential target structures and facilitates direct comparison between the different targets regarding the strength of the T-cell responses induced by the targeted DCs. The assay could be useful as a first-line screening of potential target structures on murine DCs.