E.coli O55:B5 LPS, 1 mL

From STEMCELL Technologies, this lipopolysaccharide is extracted from E. coli (wild-type S-form, serotype O55:B5) and is used as a research reagent for activating Toll-like receptor 4 (TLR4) on immune cells. When applied at 1 μg/mL to wild-type mouse macrophages, it elicits robust IL-6 production, reaching ≥ 9200 pg/mL in cell culture supernatants after 24 hours as measured by ELISA. The response is TLR4-specific: IL-6 production in TLR4 knockout macrophages is comparable to a medium-only negative control, demonstrating that this lipopolysaccharide does not activate any TLR other than TLR4. The optimal working concentration for activation is 0.01–1 μg/mL. The reagent is also employed as part of an M1 macrophage polarization workflow, where it is combined with IFN-γ to drive M1 activation of monocyte-derived macrophages cultured in serum-free media.