Objective:To elucidate the release and expression of high mobility group protein B1(HMGB1)in macrophage induced by Lipoplysaccharide(LPS).Methods:The murine macrophage-like cell line RAW264.7 was stimulated by LPS.The contents of HMGB1 protein were detected by Western blot in cultured cells supernatant

cytoplasm and nucleus.The expression of HMGB1 mRNA in cultured cell was determined by RT-PCR.The HMGB1 contents in cytoplasm and nucelus were observed using immunocytochemistry and laser confocal scanning microscopy(LCSM).Results:The contents of HMGB1 protein in supernatant could not be detected at 0～12 h

but increased gradually from 18h

reached a peak at 24 h and maintained stably at high level after the stimulation of LPS.The level of HMGB1 protein in cytoplasm increased gradually from 0 h to 48 h.The HMGB1 protein level in nucleus was higher at 0 h and decreased gradually at 12～24 h

but increased gradually at 36～48h after LPS stimulated.The expression of HMGB1 mRNA was not significantly changed at 0～18 h but enhanced significantly at 24～36 h after LPS stimulated.Conclusion:The release of HMGB1

TNF-αand IL-6 increased in macrophages induced by LPS.HMGB1 was released later than that of TNF-αand IL-6.The expression of HMGB1 mRNA is delayed. HMGB1 released to outside of the cells was come from the prior synthetic reservation in nucleus at early time.Lately new HMGB1 protein was synthesized in nucleus and was transferred into cytoplasm

which led to the level of HMGB1 in nucleus and in cytoplasm increased.