FIGURE 3.

CD4⁺ T cells play a crucial role for induction of LPS-specific antibody responses in both systemic and mucosal compartments. (a) CD4⁺ T cells were depleted using anti-CD4 depleting mAbs during vaccination to assess a role for CD4⁺ T cells for induction of LPS-specific B cell responses. At 1 week after the 2^nd vaccination with RASV strain, the levels of LPS-specific antibodies were measured in sera and fecal extracts, and numbers of LPS-specific antibody-secreting cells (ASC) were measured in the spleen and lamina propria of the small intestine (SI-LP). * ; p<0.05, ** ; p<0.01, *** ; p<0.001 vs. isotype control antibody-treated mice. (b) Bone marrow–derived dendritic cells (BM-DC) from wild-type (WT), TLR4^−/−, and Myd88^−/− mice were co-cultured with RASV strain for 48 hr in vitro. After incubation, DCs were stained for co-stimulatory molecules (CD40, CD80, CD86) and analyzed by flow cytometry. (c) CD4⁺ T cells isolated from spleen of RASV-vaccinated WT and MyD88^−/− mice were co-cultured with LPS-stimulated DCs from naïve mice spleens for 90 hr, including a final 18-hr pulse with [³H] thymidine. Cells were harvested and [³H] thymidine incorporation measured. Values given represent mean ± SD. Data are representative of ≥2 independent experiments.