By contrast, when IFNAR−/− bone marrow cells were cultured with influenza viruses, the proportion of CD11c+/MHCII+ BMDCs generated was similar to that observed in untreated cultures, suggesting that the IFNAR was required to mediate these effects. To further investigate the role of type 1 IFN, BALB/c bone marrow was cultured in the presence of GM-CSF, with or without Jap or recombinant IFN-α. The data (Fig. 5b) demonstrated that cultures treated with IFN-α showed a reduction

in BMDC production similar to that observed in cultures stimulated with Jap virus. We next examined the effects of neutralizing IFN. Cultures were treated with IFN-α in the presence or absence of neutralizing antibody to IFN-α. AZD1208 The results (Fig. 5c) showed that in the presence of neutralizing antibody the effects of IFN-α were negated and CD11c+/MHCII+ BMDC production was restored to levels corresponding to those observed in unstimulated cultures. To investigate whether the effects of influenza virus were mediated by IFN-α, cultures were treated with the Jap virus in the presence or absence of neutralizing anti-IFN-α (Fig. 5d). The addition of antibody clearly reversed the effects induced by the virus. Taken together, this evidence clearly demonstrates a role for type 1 IFN, signalling through the IFNAR, in mediating

Daporinad molecular weight responses to influenza viruses that lead to the observed changes in BMDC generation. As described above, ligands for TLRs 3, 4 and 9 were shown to initiate changes in haematopoiesis, inducing a marked reduction in BMDC production. In many cells the cytokine

TNF-α is produced in response to MyD88-dependent TLR signalling and this cytokine has also been shown to inhibit haematopoiesis19. To examine a possible role Loperamide for TNF in mediating the observed effects, recombinant TNF-α was added to bone marrow cultures containing GM-CSF. The results (Fig. 6a) show that the addition of TNF-α led to a reduction in the production of CD11c+/MHCII+ BMDC similar to that observed in cultures stimulated with influenza viruses or TLR ligands. The addition of a neutralizing antibody, anti-TNF-α (Fig. 6b), restored the production of CD11c+/MHCII+ BMDCs, confirming that TNF-α was responsible and that the antibody could abolish its effects. To assess whether TNF-α was mediating the effects of LPS and CpG ODN, bone marrow cells were cultured with GM-CSF and these stimuli in the presence or absence of the neutralizing antibody, anti-TNF-α. The resulting data (Fig. 6c) showed that anti-TNF-α had no effect on the modulation of BMDC production by LPS or CpG ODN. Data compiled from cell numbers (Fig. 6d) revealed that although there was little change in the proportion of cells displaying a CD11c+/MHCII+ phenotype, anti-TNF-α did appear to suppress the increase in cell number usually observed to occur in response to LPS and CpG ODN.