Objective To study the effects of MF59 in combination with heat-killed BCG ( hBCG) as adjuvant on the immunogenicity of Mycobacterium tuberculosis fusion protein PstS1-LEP.Methods BALB/c mice were divided into six groups from group 1 through group 6.They were immunized with PstS1-LEP+MF59 ( group 1 ) , PstS1-LEP+MF59/hBCG ( group 2 ) , PstS1-LEP+hBCG ( group 3 ) , MF59 ( group 4 ) , PstS1-LEP (group 5) and hBCG (group 6) for three times at intervals of two weeks , respectively.The mice were sac-rificed two weeks after the last immunization .The serum samples were collected for antibodies detection .The splenic lymphocytes and peritoneal macrophages were isolated and cultured with PstS 1-LEP.Indirect ELISA and sandwich ELISA were used to detect PstS 1-LEP-specific antibodies and cytokines in the supernatants of culture , respectively.Results The level of IFN-γ, IL-1β, IgG, IgG1 and IgG2a in group 1 were higher than those in groups 4, 5 and 6 (P<0.05).The level of IL-2 and IL-4 in group 1 were higher than those in groups 4 and 6 (P<0.05).The level of IFN-γ, IL-1β, IL-12, IgG, IgG1 and IgG2a in group 2 were higher than those in groups 4, 5 and 6 (P<0.05).The level of IL-2 was higher in group 2 than that in groups 4 and 6 (P<0.05). The level of IL-4 in group 3 was higher than that in group 4 ( P=0.05 ) .The level of IL-1βin group 3 were higher than that in groups 4 and 5 ( P<0.05 ) .The level of IgG was higher in group 3 than that in groups 4 and 6 (P<0.05).IgG1 level in group C was up-regulated in comparison with that in groups 4, 5 and 6 (P<0.05 ) .Conclusion hBCG as PstS1-LEP adjuvant induces a shift towards Th 2-type immune response , while MF59 induces Th1/Th2-type immune response.The combination of MF59 and hBCG inhibits the secretion of IL-4 by spleen lymphocytes , but enhances the secretion of IL-12 by macrophage .