Abstract： Aim To investigate the effect of respiratory infection bacterial combination vaccine on immune efficacy.Methods Six types of respiratory tract infection bacteria(Streptococcus hemolyticus,Haemophilus influenzae type B,Streptococcus pneumoniae,Staphylococcus aureus,Pseudomonas aeruginosa,and Klebsiella pneumoniae)were isolated and cultured to produce bac-terial vaccines.According to the mass concentration of the combined vaccine,they were divided into the control group(physiological saline),low-level group(0.1 g/L vaccine),medium level group(0.3 g/L vaccine)and high-level group(0.5 g/L vaccine).Each group of vaccines was acted on human peripheral blood mononuclear cells in vitro,and the proliferation activity of mononuclear cells,changes in lymphocyte phenotype,and cytokine levels were detected.Each group of vaccines was acted on SPF grade mice in vivo,the delayed type hypersensitivity response,spleen index,thymus index,phagocytic index,and serum hemolysin content of each group of mice were measured.Results The proliferative activity of mononuclear cells,levels of interferon-γ and interleukin-2 in human peripheral blood of all groups were increased with the increase of time,and with higher mass concentration of combined vaccine,the levels of all indicators were higher in the same time(P＜0.05).Compared with the control group,the levels of CD4+and CD 19+of mononuclear cells in the low,medium and high-level groups were increased,while the levels of CD8+were decreased,with higher mass concentration of the combined vaccine,the variation of each index level was more obvious(P＜0.05).Compared with the control group,the delayed type hypersensitivity response,spleen index,thymus index,phagocytosis index and hemolysin optical density of mice in low,medium and high-level groups were increased,and the levels of each index were increased with the higher the mass concentration of combined vaccine(P＜0.05).Conclusion The bacterial combined vaccine for respiratory tract infection can improve the cellular and humoral immunity,and the best immune effect can be obtained when the concentration of the combined vaccine is 0.5 g/L.