Activation of macrophages and dendritic cells (DCs) in the mediastinal lymph nodes (mLNs) by Codium fragile polysaccharides (CFPs). (A) C57BL/6 mice were intranasally treated with CFPs and mLN, and bronchoalveolar lavage (BAL) fluid was collected. (B) The dose-dependent effect of CFPs on CD40, CD80, and CD86 expression in macrophages and DCs, as analyzed by flow cytometry (n = 6 mice, two-way ANOVA, *, p < 0.05 vs. 0 mg/kg in DCs; **, p < 0.01 vs. 0 mg/kg in DCs; ##, p < 0.01 vs. 0 mg/kg in Macrophages). (C) The time-dependent effect of CFPs (50 mg/kg) on the expression of costimulatory molecules in macrophages and DCs is shown. (n = 6 mice, two-way ANOVA *, p < 0.05 vs. 0 h in DCs; **, p < 0.01 vs. 0 h in DCs; #, p < 0.05 vs. 0 h in Macrophages: ##, p < 0.01 vs. 0 h in Macrophages). (D) The concentration of interleukin (IL)-6, IL-12p70, and tumor necrosis factor (TNF)-α levels in bronchoalveolar lavage (BAL) fluid, as analyzed by ELISA. (n = 6 mice, two-way ANOVA, *, p < 0.05 vs. 0 mg/kg; **, p < 0.01 vs. 0 mg/kg).