[Effect of high mobility group B1 protein on the function of phagocytosis and the expression of I-A/-E of peritoneal macrophages in mice].
OBJECTIVE
To investigate the effect of extracellular high mobility group B1 protein (HMGB1) on the immunological function of macrophages.


METHODS
Peritoneal macrophages from mice were stimulated by concentration gradient HMGB1 in vitro. Male BALB/c mice were divided randomly into control group (normal saline, i.p.), low or high dose group (treated with HMGB1 0.2 microg or 20 microg per mouse, respectively, i.p.). Phagocytosis of neutral red and I-A/-E expression of macrophages was assayed.


RESULTS
(1) HMGB1 regulated the phagocytosis of macrophages in a time- and dose-dependent manner, but it did not regulate the expression of I-A/-E in vitro. Moreover, the phagocytosis of macrophages was significantly enhanced by stimulating of HMGB1 at a concentration of 10 microg/L as compared with other stimulating concentrations at culture-hour 6 and 12 (P<0.05 or P<0.01). (2) The capacity for phagocytosis of macrophages was reduced from 43% to 67% when the mice were challenged with HMGB1 in vivo. However, as compared with animals in control group, neutral red phagocytosis of macrophages was depressed markedly in the animals inflicted with high dose HMGB1 for 24 hours (P<0.05). The I-A/-E expression of macrophages was up-regulated markedly in the animals inflicted with low dose HMGB1 for 48 hours as compared to animals treated with normal saline and high dose HMGB1(P<0.05 or P<0.01).


CONCLUSIONS
High dose HMGB1 can depress the phagocytosis of macrophages, and low dose HMGB1 can enhance macrophage-mediated immunity. Moderate HMGB1 loading is beneficial to immune defense.
Wang
Zhong-Tang
ZT
Department of Plastic Surgery, Zhongshan Hospital, Xiamen University, Xiamen 361004, China. wangkingking@hotmail.com
Yao
Yong-Ming
YM
Sheng
Zhi-Yong
ZY
D000818:Animals; D002478:Cells, Cultured; D024243:HMGB1 Protein / Q000494:pharmacology*; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010587:Phagocytosis / Q000187:drug effects*
D024243:HMGB1 Protein; D000949:Histocompatibility Antigens Class II; C024138:I-E-antigen