Fluorescence was measured using a Luminex model 100 XYP (Luminex, USA). Data are shown as the cytokine concentration above background in pg/ml. Statistical analysis was performed with Prism software (Graphpad Software Inc., San Diego, version 4.00). An unpaired two-tailed t-test was used in Fig. 2. One-way ANOVA followed by a Bonferroni’s multiple comparisons test was used in Fig. 4C. One-way ANOVA followed by a Kruskal–Wallis test and Dunn’s multiple comparison test see more was used in all other experiments. To investigate the role of TLR2 in BLP-mediated local and systemic IAV-specific T-cell and

B-cell activation, B6.129-Tlr2tm1Kir/J mice (TLR2KO) and C57BL6/J (wt controls) were immunized i.n. with BLP-SV (A/Sidney/5/97, H3N2). As a control, wt mice were i.m. immunized with SV alone. Fourteen days after the last immunization, KRX-0401 cells from the draining lymph nodes (dLN) and spleen were isolated and analyzed for IAV-specific IFN-? producing cells and IAV-specific B-cells. In the local dLN significantly reduced numbers of IAV-specific IFN-? producing T-cells (Fig. 1A) and lower numbers of IAV-specific B-cells (Fig. 1B) were observed in TLR2KO mice compared to the number of cells in wt control mice. Similar to the

observations made in the local dLN, also significantly lower numbers of IAV-specific IFN-? producing T-cells (Fig. 1C) and a slight reduction in IAV-specific B-cell numbers (Fig. 1D) were observed in the spleen of TLR2KO mice compared to vaccinated wt mice. These data indicate that induction of IAV-specific IFN-? T-cell and B-cell responses both in the local dLN and spleen requires interaction

of BLP with TLR2. The IAV-specific IFN-? T-cell responses in the dLN of wt controls were slightly higher after i.n. BLP-SV immunization compared PAK6 to the responses after i.m. immunization with SV alone although this did not reach statistical significance. The systemic IFN-? T-cell response observed in spleen was similar after i.n. and i.m. immunization (Fig. 1). Similar observations were made when BALB/c mice were immunized i.n. and i.m. with BLP-SV and SV, respectively (Table 1). To investigate how i.n. BLP-SV vaccination affects systemic T-cell differentiation we analyzed IL-5 and IL-17A production of activated splenocytes. After i.n. BLP-SV vaccination the enhanced IAV-specific IFN-? T-cell responses coincided with a slightly increased production of IL-17A cytokine (Fig. 2A) and significantly decreased secretion of IL-5 cytokine (Fig. 2B) compared to SV i.m. vaccinated mice. Together these results indicate that the IAV-specific T-cell and B-cell responses induced after i.n. BLP-SV administration are TLR2 dependent and results in Th1/Th17 skewing. Activation of B-cells in mucosa-associated lymphoid tissues is associated with production of SIgA at the mucosal surfaces [8] and [9].