4.5. Enzyme-Linked Immunosorbent Assay (ELISA) for TNF-α, IL-6 and PGE2

BV2 microglial cells were cultured in complete growth medium containing CTL (0, 2.5, 5, and 10 μM) and 1 μg/mL of LPS or vehicle. Culture supernatants were collected after 4 h and the level of TNF-α was determined with TNF-α ELISA kit (ExCell Bio, Shanghai, China). The level of IL-6 was determined with IL-6 ELISA kit (ExCell Bio, Shanghai, China) 8 h later. Moreover, BV2 microglial cells were treated for 24 h for PGE₂ assay using ELISA kit from ENZO (ENZO, Farmingdale, NY, USA). TNF-α, IL-6, and PGE₂ concentrations were measured at 450 nm according to the manufacturer’s protocol.