I'm trying to induce inflammation in BV2 cell line. I seed 4*10^5/well cell in 6-well plate, add 1ug/ml LPS for 4 or 23.5 hours, then add 10uM nigericin for 30 minutes. I can detect NLRP3 expression higher after LPS treatment, but no IL18 can be detected in supernatant by mouse IL18 ELISA kit. Does any one have similar problem?