Adjuvant Effect Of Whole Peptidoglycan Of Bifidobacterium To Recombinant Hepatitis B Surface Antigen

Bifidobacterial peptidoglycan has powerful immunostimulating activity eitherin vivo or in vitro, but whether whole peptidoglycan (WPG) can enhance immuneresponse to recombinant hepatitis B surface antigen is not clear. In this study, weexplore the adjuvant effect and related mechanism of WPG of Bifidobacterium. WPG adsorbed rHBsAg by means of PBS, glutaraldehyde-coalescence andADP-coalescence, which was purified from Bifidobacterium bifidum, ELISAassay was used to detect the adsorption ratio. WPG coupled with rHBsAg wasadministered into BALB/c mice, adverse side-effects and body weight wereobserved in the following weeks. After 8 weeks inoculated with rHBsAg, all micewere sacrificed, thymus index and spleen index were measured, ELISA assaywas used to detect the anti-HBs-IgG and IgG subtype in serum, LDH releaseassay was used to detect the activity of NK cell and CTLs in splenic lymphocytes,MTT assay was used to detect the proliferation of splenic lymphocytes, ELISAassay was used to detect cytokine inductions of splenic lymphocytes, all in vitro. Both glutaraldehyde and ADP have no promotion of rHBsAg adsorption toWPG compared with PBS. After inoculation into mice, there was no adverseside-effect observed in mice body. All mice grew well, body weight increasednormally, but weight of thymus and spleen were higher in mice administered withWPG. Compared with those mice administered with rHBsAg alone or plus alumadjuvant, WPG induced higher seroconversion ratio, higher levels ofanti-HBs-IgG as well as IgG subtype; in vitro, proliferation activity of spleniclymphocytes was enhanced, cytokine induction was promoted, more powerfulcytotoxicity of NK and CTL was stimulated. The results aboved suggested that WPG can adsorb rHBsAg in certainbuffered solution and has no adverse side-effect as an adjuvant. WPG ofbifidobacterium has adjuvant effect and the mechanisms may be as follows:WPG can increase the weight of thymus and spleen, which help to maintain thefunction of lymphous immune organs; WPG can modulate immune response torHBsAg by enhancing the proliferation and cytokine induction of spleniclymphocytes; WPG can promote NK and CTL activities to clear virus. Takentogether, compared with alum adjuvant, WPG can stimulate stronger humoralimmune response and cellular immune response to rHBsAg simultaneously.