An Analysis Of Mechanism Of The Effect That LPSp Increases The Production Of Anti-HBs In Mice Immunized With HBsAg

Objective: To investigate the mechanism of the effect of avirulentPantoea agglomerans lipopolysaccharide (LPSp), that acting as adjuvantfor HBsAg on the production of anti-HBs in mice.Methods: Peritoneal macrophages were harvested from BALB/c miceinjected i.p. with 8ml lps-free RPMI 1640. The peritoneal cells werepurified, identified and counted, then were adjusted to 1×106/ml.Theperitoneal cells were pulsed in vitro with HBsAg+LPSp, HBsAg, LPSp,NS respectively. After cultured in vitro, the adherent macrophages weredigested and collected. (1) BALB/c mice received an i.v. injection ofHBsAg-pulsed peritoneal macrophage,treated or not with LPSp in vitro .Five days later, all mice received a boost of soluble HBsAg i.v. Serawere harvested 15 days, 20 days and 25 days after the first immunization.ELISA determined serum levels of anti-HBs IgG. (2) After peritonealmacrophages were pulsed with HBsAg for 6h, treated or not with LPSp,the phagocytosis function of macrophages were detected. (3) Afterperitoneal macrophage were pulsed with HBsAg, treated or not with LPSp,the culture supernatants were harvested and assaied for TNF-αand NO .(4) HBsAg-pulsed peritoneal macrophage in the presence or absence ofLPSp were injected in the hind footpads of syngeneic mice. Five dayslater, lymph nodes cells were harvested and cultured with HBsAg, IL-4and IFN-γin the supernatants were quantitated by two-site ELISA.Results: (1) The anti-HBs IgG titers from mice immunized withHBsAg-pulsed peritoneal macrophage treated with LPSp were higher thanthose immunized in the absence of LPSp (p<0.05). (2) The phagocytosisrate of LPSp-treated peritoneal macrophages was higher than that ofuntreated macrophages (p<0.05). (3) The levels of TNF-αand NO ofLPSp-treated peritoneal macrophage were higher than that of untreatedmacrophages(p<0.05) . (4) HBsAg-pulsed peritoneal cells in thepresence of LPSp could induce higher production of IL-4 than which inthe absence of LPSp (p<0.05).Conclusion: LPSp could act as the adjuvant of HBsAg, andeffectively increase the anti-HBS in mice immunized with HBsAg .Themechanism could be: (1) LPSp could activate macrophages.①increasingthe phagocytosis function of macrophages. ②stimulating the productionof TNF-αand NO of macrophages.(2) LPSp could stimulate HBsAg-pulsedmacrophages to induce production of IL-4 of lymph nodes cells,suggesting that LPSp could stimulate HBsAg-pulsed macrophages toinduce the activation of Th2-type lymphocyte and helping the productionof anti-HBS. (3) LPSp couldn't stimulate the production of IFN-γinduced by HBsAg-pulsed macrophages, suggesting that LPSp couldn'tstimulate the activation of Th1-type lymphocyte induced byHBsAg-pulsed macrophages.