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目的 :探讨大肠杆菌热不稳定肠毒素B亚单位 (LTB)的免疫调节功能及其可能的机制。方法 :用SephacrylS 10 0凝胶柱层析纯化LTB蛋白。选用BALB/c小鼠 ,以鸡溶菌酶 (HEL)为抗原 ,经鼻黏膜单独免疫 ,或以不同剂量的LTB为佐剂与HEL共免疫。用ELISA法检测血清和肠分泌液中HEL特异性抗体的水平。用3 H TdR掺入法 ,体外测定LTB蛋白对刀豆蛋白A(ConA)及同种异体抗原介导的淋巴细胞增殖反应的影响。结果 :HEL单独免疫组血清中仅有弱的抗HELIgG ,未检测到抗HELIgA ,且其肠分泌液中亦未见HEL特异性IgA抗体。但加用LTB佐剂的 3个组 ,其血清中抗HELIgG、IgA的水平及肠分泌液中抗HELIgA的水平均显著高于HEL单独免疫组 (P <0 .0 0 1)。体外实验显示 ,LTB可明显抑制ConA及同种异体抗原介导的淋巴细胞增殖反应。结论 :我们制备的LTB蛋白对免疫系统具有双向的调节功能 ,既可作为有效的黏膜佐剂 ,辅佐外来抗原刺激机体产生黏膜免疫应答 ,又具免疫抑制效应 ,有效地抑制淋巴细胞活化。LTB免疫调节功能的发挥 ,可能与其作用于机体的途径有关
Objective: To investigate the immunoregulatory function of heat-labile enterotoxin B subunit (LTB) in Escherichia coli and its possible mechanism. Methods: LTB protein was purified by Sephacryl 10 gel column chromatography. BALB / c mice were selected and co-immunized with HEL alone. Nasal mucosa was immunized alone or with varying doses of LTB as an adjuvant. The levels of HEL-specific antibodies in serum and intestinal secretions were measured by ELISA. The effects of LTB on ConA and alloantigen-mediated lymphocyte proliferation were determined by 3 H TdR incorporation. Results: HEL anti-HELIgG was not detected in sera of HEL alone group, anti-HELIgA was not detected, and HEL-specific IgA antibody was not found in intestinal secretions. However, the levels of anti-HELIgG and IgA in sera and the levels of anti-HELIgA in intestinal secretions were significantly higher in the three groups with LTB adjuvant than those in HEL alone group (P <0.01). In vitro experiments show that LTB can significantly inhibit ConA and alloantigen-mediated lymphocyte proliferation response. CONCLUSION: The LTB protein we prepared has bi-directional regulatory function on the immune system, which can be used as an effective mucosal adjuvant to stimulate the body to produce mucosal immune responses as well as immunosuppressive effects and effectively inhibit lymphocyte activation. LTB immunomodulatory function, may be related to its role in the body’s pathways