Robust Th17 response to intranasal group A streptococcal infection requires IL-6 produced by CD301b+CD11b+CD103- migratory dendritic cells (MUC2P.937)

Intranasal (i.n.) Group A Streptococcal (Streptococcus pyogenes - Sp) infections generate a vigorous Th17 response. We tested the hypothesis that a specific dendritic cell (DC) subset in the nasal associated lymphoid tissue and cervical lymph nodes (CLN), preferential sites of colonization and lymphatic drainage site for i.n. Sp, are responsible for this skewing of the T cell response. The hypothesis was tested by tracking polyclonal Sp peptide:MHCII-specific CD4+ T cells mice lacking specific DC subsets. We found that Sp peptide:MHCII-specific Th17 formation depended on an IL-6 producing CD301b+ CD11b+ CD103- migratory DC population in the CLN. The results contrast with other findings implicating CD11b+ CD103+ DC in Th17 induction in the intestinal mucosa. Therefore, different DC subsets are responsible for Th17 generation through different mucosal surfaces.