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For a long time, researchers have made great achievements in anti-infective immunity, but the research on anti-infective immunity is still a hot issue in the medical field. Especially in recent years, some infectious diseases have revived after being controlled, and many new infectious diseases have begun to spread, such as the recent swine flu epidemic, which poses a serious threat to human health. Therefore, the study of anti-infective immunity is of great value. This paper only briefly introduces the role of antibodies in anti-infective immunity.

Keywords antibody; Anti-infection immunity; function

China Library Classification Number R392 Document Identification Number A1006-1959 (2009) 06-0241-02.

In the field of immunology research, anti-infective immunity plays an important role. Researchers have made great achievements in this field, but the research on anti-infective immunity is still a hot issue in the medical field. Especially in recent years, some infectious diseases have revived after being controlled, and many new infectious diseases have begun to spread, such as the recent swine flu epidemic, which poses a serious threat to human health. Therefore, the study of anti-infective immunity is of great value. This paper only briefly introduces the role of antibodies in anti-infective immunity.

Direct antibacterial effect of 1 antibody

For a long time, many medical workers believe that antibodies can only bind to microorganisms (antigens) through variable regions, and do not directly kill or dissolve microorganisms, but only activate complements or regulate them.

Use can achieve the purpose of antibacterial. However, antibodies have been found to have a direct bactericidal effect. For example, IgM monoclonal antibody (MAb) against the membrane protein of Acinetobacter baumannii is bactericidal by inhibiting the absorption of iron; Another example is that IgM and IgG antibodies against Borrelia burgdorferi surface protein destroy the surface protein shell of Borrelia burgdorferi, resulting in the effect of killing bacteria without complement; Antibodies bind to extra-intestinal parasites, inhibit the activities of parasites and have the effect of expelling insects; Anti-Cryptococcus neoformans acyl sphingosine antibody and cell wall-associated melanin antibody can inhibit the growth of Cryptococcus neoformans cells without complement. The antibody of mannose protein in Candida albicans cells can block the transformation of Candida albicans from yeast type to mycelium type. The obvious example of antibody direct antimicrobial is the anti-idiotypic antibody that neutralizes Pichia pastoris and kills toxin MAb. Because of its in-antigen imaging effect, it has a wide range of antimicrobial effects.

2. Immunomodulatory effect of antibody

2. 1 antibody and inflammation;

Whether antibodies promote or inhibit inflammation is related to the specificity, type and concentration of antibodies, and different types of antibodies have different effects. There are irritating and inhibitory FcR in the body, and the antibody concentration is related to the size of antigen-antibody complex. IgM is usually pro-inflammatory, because it is the strongest antibody to activate complement, and IgM is produced in the early stage of infection, so natural IgM is the key factor to fight infection in the early stage of bacterial and viral infection. However, IgM can also weaken the inflammatory response. For example, Streptococcus pneumoniae-specific human IgM can down-regulate the release of neutrophils stimulated by Streptococcus pneumoniae. Polyclonal IgM products can reduce inflammatory complications, complement and oligodendrocyte activation after cardiac surgery. IgG molecules have pro-inflammatory or anti-inflammatory effects, which are related to IgG subtypes, different concentrations and the interaction with FcR. Therefore, the type of antibody, the concentration of target cells and antigens, and FcR cross-linking can promote or inhibit inflammation.

2.2 The role of antibodies in cellular immunity: It is generally believed that antibodies play a role in body fluids and do not play a role in intracellular infections or tumors. However, it has been proved that antibodies have amazing effects in anti-cancer and anti-infective agents that rely on cellular immunity. And the interaction between antibody and antigen affects the immune response to antigen, which is helpful to form cellular immune response and specificity. For example, mice vaccinated with kala-azar vaccine must have natural IgM to produce CD8? +T cell response, phagocytes secrete IL-4 to activate specific cytotoxic T lymphocytes (CTL). Animals lacking antibodies and complements can not produce cellular immunity, but can recover with normal mouse serum. Another example is that antibodies participate in the defense response to repeated reproductive tract infections caused by Chlamydia trachomatis (ct). Therefore, both FcrR knockout mice and wild-type control mice were infected with Ct at the same time, and the upward infection of the former increased. In addition to promoting macrophages to kill infected epithelial cells, anti-chlamydia antibodies can also enhance the induction of FcR? +/+mouse TH 1 reaction (with FcR? -/-mouse comparison). Can these antibodies enhance FcR in vitro? The ratio of+/+antigen presenting cells (APC) activated by Th 1.

2.3 Effect of antibody on humoral immune response: Exogenous administration of antibody can not only produce passive immune effect, but also regulate humoral immune response of the body, that is, it can enhance humoral immune response in the presence of corresponding antigen. For example, BALB/C mice were immunized with Streptococcus mutans or Streptococcus mutans plus corresponding monoclonal antibodies. Results: Compared with the former, the antibody quantity, Ig category (serum IgG, mucosal SIgA) and antibody specificity of the latter have changed, which may be caused by the change of APC processing antigen caused by foreign antibodies. Intravenous or intranasal injection of human Ig into pneumonia model mice has a defensive effect before the attack of Streptococcus pneumoniae, and the level of antibody against Streptococcus pneumoniae hemolysin produced by it is higher than that of the control group (Ig is not given), and it has greater resistance to subsequent reinfection, even after the removal of human Ig. This strongly shows that animals treated with IVIG have strengthened the development of adaptive immunity. Pneumonia caused by staphylococci has also been reported similarly.

Antibodies have been used to immunize human or animal pathogens (such as bacteria and viruses). The Venezuelan equine encephalitis vaccine treated with formaldehyde forms a complex with the corresponding antibody IgG, which can increase the immune response of rhesus monkeys to the vaccine. The antibody induced is mainly IgG, which can induce secondary immune response faster than IgG and IgM induced by single vaccine. In mouse experiments, it was observed that the immune complex produced a sustained defense effect 24 hours after inoculation, while it took 8 days for a single antigen to produce a defense effect. Monkey virus 5(SV5) is a paramyxovirus, and its antibody binds to Staphylococcus aureus or protein A. When this complex is used as an immunogen to induce an immune response, the replication of SV5 in the lungs of infected mice is reduced, and the CTL of the corresponding virus can be detected.

Antibodies are used for treatment.

Studies have confirmed that passive immunotherapy with polyclonal neutralizing antibody serum after simian immunodeficiency virus (SIDV) infection can promote rhesus monkeys to produce high titer neutralizing antibodies and block lentivirus infection. The monkey treated with neutralizing antibody can maintain the plasma level of ≤ 103 virus particles /ml, and ≤ 103 infected virus particles/106 PBMC and lymph node cells, and the onset is delayed. After 20 weeks of survival, there was significant difference in humoral immunity between IgG treatment group and control group. IgG significantly promoted the production of neutralizing antibodies. This shows that the neutralizing antibody can reduce the viral load at the early stage of infection or keep it at an unpredictable level within 3 ~ 5 years, and the antibody can promote the neutralizing antibody to mature again. Experts confirmed that C57BL/6 mice were immunized with recombinant hepatitis B surface antigen (HBsAg), HBsAg+ anti -HBs, DNA and immune complex +DNA respectively, and found that the immune complex +DNA group had the best effect. Including reducing serum HBsAg level, stimulating anti -HBs antibody level, inducing TH 1 mediated immune response and down-regulating the expression of m-sAg in hepatocytes. These studies show that the antibody response induced by foreign antibodies may be regulated by the antibody itself in the antigen-antibody complex and change the antibody response. Inoculation of HBsAg and the corresponding MAb complex may lead to the formation of new epitope antibodies of vaccine immunogens, which may have direct clinical application value. Because only HBsAg vaccine is used, there are relatively many people without serum antibodies, and other target epitopes may be recognized by these people. It is reported that the use of HBsAg and MAb complex can stimulate the proliferation of immune T lymphocytes more effectively than the use of HBsAg alone. Therefore, immune complex vaccine is a promising method to treat chronic hepatitis B.

refer to

[1] casadevall A, Pimfski L. A new concept of antibody-mediated immunity [J]. Infection Immunity, 2004,72 (11): 6191-6196.

[2] Guo Shishi. Some new advances in anti-infective immunity [J]. China Journal of Infection Control .2006, 1.