Dendritic cells recruitment and in vivo priming of CD8(+) CTL induced by asingle topical or transepithelial immunization via the buccal mucosa with measles virus nucleoprotein

The buccal mucosa, a prototype of pluristratified mucosal epithelia, contai ns a network of directly accessible class II+ epithelial dendritic cells (D C), similar to skin Langerhans cells. We showed that a single buccal immuni zation with measles virus nucleoprotein (NP), by either topical application onto or intradermal injection in the buccal mucosa, induced in vivo primin g of protective class I-restricted specific CD8(+) CTL. Both routes of immu nization with NP induced a rapid recruitment of DC into the mucosa, which p eaked at 2 h and decreased by 24 h. Treatment of mice with Flt3 ligand resu lted in an increased number of DC in the buccal mucosa and enhanced the fre quency of IFN-gamma -producing NP-specific effectors and the NP-specific CT L response generated after buccal immunization with NP. Finally, NP-pulsed bone marrow-derived DC induced NP-specific IFN-y-producing cells upon adopt ive transfer to naive mice. These data demonstrate that a viral protein del ivered to DC of the buccal mucosa induces in vivo priming of protective ant i-viral CD8(+) CTL.