Although they are not immune-compromised, human MO-DCs do not sense leptospires through TLR4, and yet we measured up-regulation of the markers and cytokines upon infection with Leptospira. We also found in BM-DCs that except for CD40, the other activation markers, as well as DC-SIGN, did not rely on TLR4 signaling, whereas cytokine secretion was decreased in TLR4-/- BM-DCs. Here, TLR4 is linked to infection.