Expression of Th cytokines in mice after BMT. Spleen and lymph nodes of chimeric mice 7 days after transplantation were removed, ground and then incubated in RPMI medium with phorbol myristate acetate, ionomycin and brefeldin A for 6 h. The percentages of CD4+ T cells secreting cytokines such as IFN-γ (a) and IL-2 (b) in TLR4−/− mice and TLR4+/+ mice were determined by FACS. The percentage of T cells secreting IFN-γ and IL-2 in the TLR4−/− mice group compared to TLR4+/+ mice was significantly decreased (P<0.05). (c) TLR4+/+ or TLR4−/− as donor mice: the production of cytokines in sera derived from recipient BALB/c mice was analyzed on day 7 post-transplantation by ELISA. The levels of cytokines (IFN-γ and IL-10) in the TLR4−/− group, as compared to the TLR4+/+ donor mice group, were significantly increased. IL-2 levels in the TLR4−/− mice group were significantly lower than in TLR4+/+ group (P<0.05), while IL-4 levels were not significantly different between both groups (Figure 7c). Data shown are the mean±s.d. from at least three mice (*P<0.05, **P<0.01). BMT, bone marrow transplantation; ELISA, enzyme-linked immunosorbent assay; FACS, fluorescent activated cell sorting; IFN-γ, interferon-γ TLR4, Toll-like receptor 4.