A state in which the immune response to a specific antigen is suppressed
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Immune tolerance refers toantigenOfimmuneReaction is subject toinhibitionStatus of.animalIt is in a state of tolerance to its own components, but in a narrow senseimmuneTolerance refers to the same state as this self tolerance.
organismimmune systemA state of specific non response to an antigen after exposure to that antigen.Individuals who have developed immune tolerance to a certain antigen cannot generate routine detectable immune response or immune response when they contact the same antigen again, but they still have immune response ability to other antigens.Immune tolerance belongs to the category of specific immune toleranceB lymphocytesTolerance, or both, without specificityDelayed allergy, or there is no specific antibody in the blood stream, or both cases coexist.Specific anergy can be obtained naturally or artificially induced by simulating natural acquisition.The former is calledAutoimmunityTolerance or natural tolerance;The latter is calledAcquired immune toleranceSex.Autoimmune tolerance shows that the body itself does not produce immune response to its own tissues.A large number of experimental results have proved that immune tolerance can be induced in embryonic stage, newborn stage or adult stage.The rule is that the earlier the individual development period, the higher the success rate of induction.It is not easy to induce immune tolerance by injecting antigen into adult animals.But the antigen is injected at the same timeImmunosuppressant, which can induce immune tolerance to the antigen.Even if there is no drug effect in the future, re injection of the same antigen can also produce immune tolerance.Although both T cells and B cells generate immune tolerance after antigen injection, there are great differences between T cells and B cells in the dose of antigen required to induce immune tolerance and the duration of tolerance maintenance.T cells need less dose and maintain for a long time.In addition, the nature of antigen, animal strain, individual immune status and injection route have a direct impact on the induction of immune tolerance.The mechanism of immune tolerance is very complex.Clinically, induction of immune tolerance can help to treat allergic reactionsAutoimmune diseaseAnd prevent graft rejection.Some people use carrier tolerance induction experiment to reduceImmunoglobulin EEncouraging progress has been made in the production of IgE antibodies to treat allergic diseases.
Performance characteristics
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(1) Immune non responsiveness to self components is not determined by heredity, but acquired.
(2) Autoantigens are responsible for the formation of autotolerance.
(3) The antigen reactivity of lymphoid cells has no directional expression of both autoantigens and non autoantigens. If the reactive cells to themselves are removed, an immune mechanism only to non autoantigens can be formed.The immune tolerance to not only self components but also foreign antigens can also be formed in the acquired day.
Induced condition
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Body factors
① Age of animals: It is easiest to establish immune tolerance in embryonic stage, followed by newborn stage, and it is more difficult in adult stage.This may be related to the maturity of the immune system at various stages of the body;
② Immunoreactivity: individuals with strong immune reactivity are not easy to produce immune tolerance, and animals with immune deficiency, whether spontaneous or using immunosuppressants, are easy to induce immune tolerance;
③ Species of animals: intestinal mice and sheep are difficult to induce immune tolerance, rabbits and monkeys can only induce immune tolerance in embryonic stage, and mice, rats and hamsters are relatively easy to induce immune tolerance;
④ Impact of immunosuppressants: This is a factor of exogenous non-specific suppression of immune function.High dose X-ray irradiation and various immunosuppressants can inhibit all immune responses, while the immune tolerance to the antigen can be induced by giving the antigen at the same time as giving the appropriate dose of drugs.
Antigenic factors
① Nature of antigen: Antigen substances that can induce immune tolerance are called tolerogens.It is mainly resistant to original protein, bacterial or viral antigen, hapten andSynthetic polypeptide。Antigens that are not easily cleared from the body are easier to induce immune tolerance than those that are easily cleared.The tolerance that is not easy to be metabolized in vivo can maintain immune tolerance for a longer time than the tolerance that is easy to be metabolized;
② The route and mode of antigen injection;Intradermal and subcutaneous injection are easy to induce immune response, followed by intramuscular injection, and intravenous injection is less effective. Oral and digestive tract ingestion of antigens are easy to induce immune tolerance.If immune adjuvant is used when injecting antigen, it is not easy to cause immune tolerance;Freund's adjuvant mainly induces IgG antibodies, and alum mainly induces IgE antibodies.
③ Dose of antigen: there are many factors affecting the induced immune tolerance, and it is difficult to determine a fixed amount of induction.It is generally believed that moderate dose is easy to induce immune response, but not easy to induce immune tolerance.It is easy to induce immune tolerance in large doses of thymus independent antigen;Thymus dependent antigenSmall or large doses can induce immune tolerance.The immune tolerance induced by high dose antigen is called high dose immune tolerance, and the immune tolerance induced by low dose antigen is called low dose immune tolerance;
④ Density of determinant cluster: the greater the density of determinant cluster, the easier to induce immune tolerance.
