Mucosal immune features to phosphorylcholine by nasal Flt3 ligand cDNA-based vaccination.

Phosphorylcholine (PC) is an immunodominant epitope in some pathogens including Streptococcus pneumoniae and it is well-known that PC-specific antibodies (Abs) play a key role in the induction of protective immunity against pneumococcal infection. In this study, we examined whether nasal administration of DNA plasmid encoding Flt3 ligand gene (pFL) as a mucosal adjuvant plus PC-conjugated keyhole limpet hemocyanin (PC-KLH), would elicit PC-specific immune responses, and characterized mucosal immune responses to PC induced by this nasal vaccination. Nasal immunization with pFL plus PC-KLH enhanced induction of PC-specific IgA and IgM Abs in airway secretions when compared with mice given PC-KLH with or without empty plasmid gene (pORF) as controls; in addition to the mucosal immune responses, PC-specific immune responses in serum were also induced.