What Is Immunogenicity?

Immunogenicity. It refers to the property that can cause an immune response, that is, the antigen can stimulate specific immune cells, activate the immune cells, proliferate and differentiate, and finally produce the characteristics of immune effector antibodies and sensitized lymphocytes. Whether a substance can become an antigen, first of all, Depending on the nature of the substance, for example, the molecular weight of all immunogenic substances is relatively large, usually above 10,000, and those below 4,000 are generally not immunogenic; the antigen substance must have a certain chemical composition and structure. Some simple organic molecules cannot elicit an immune response by themselves, but can bind to the corresponding antibodies or sensitized lymphocytes that have been produced. This substance is called a hapten. (Haptens are not immunogenic.) After a hapten is bound to a protein Can obtain immunogenicity and become a complete antigen. (Ding Mei) ^[1]

Immunogenicity

Immunogenicity. It refers to the property that can cause an immune response, that is, the antigen can stimulate specific immune cells, activate the immune cells, proliferate and differentiate, and finally produce the characteristics of immune effector antibodies and sensitized lymphocytes. Whether a substance can become an antigen, first of all, Depending on the nature of the substance, for example, the molecular weight of all immunogenic substances is relatively large, usually above 10,000, and those below 4,000 are generally not immunogenic; the antigen substance must have a certain chemical composition and structure. Some simple organic molecules cannot elicit an immune response by themselves, but can bind to the corresponding antibodies or sensitized lymphocytes that have been produced. This substance is called a hapten. (Haptens are not immunogenic.) After a hapten is bound to a protein Can obtain immunogenicity and become a complete antigen. (Ding Mei) ^[1]

Antigenic immunogenicity

The immunogenicity of an antigen first depends on its own chemical properties, but the same antigen can be highly immunogenic to different species of animals or different individuals of the same species, and can show great differences. The originality is determined by its chemical nature and host factors. Immunogenic substances are called immunogens.

Many natural substances can induce

Whether an immunogenic substance can induce an immune response after entering the body, in addition to the above-mentioned chemical basis, is still affected by host factors, and is a more important factor.

Immunogenic heterogeneity

Under normal immune function conditions, only xenogeneic or allogeneic immunogenic substances can induce a positive immune response of the host, that is, only "non-existent" antigens can cause a positive immune response. This is because the immune system is resistant to "self" antigens during the development of the individual and cannot recognize them, while it can recognize "non-existent" antigens. Therefore, the further the antigen source is related to the host germline, the stronger its immunogenicity, such as microbial antigens, heterologous serum proteins and other substances are strong immunogens to humans. On the other hand, the germline relationship is closer, and the immunogenicity is also weak. For example, duck serum protein is weakly immunogenic to chickens and strong immunogenic to rabbits. It has been proved that physiological autoimmune responses can also be induced in normal individuals, and pathological autoimmune responses can only be straightened beyond a certain range.

Immunogenic host heredity

The fact that there is a significant difference in the resistance to nodular infection among different individuals of the same animal has been known for a long time, but the reason cannot be explained, only the individual differences are used to explain it. Thereafter, different inbred animals were immunized with known synthetic antigens. Each inbred animal had the same genetic background. As a result, it was found that some strains can produce antibodies, which are called high responders. Some strains do not produce antibodies and are called nonrespondre strains. For example, the application of the synthetic antigen dinitrobenzene-poly-l-lysine (DNP-poly-LL) can cause a response in GP strain 2 of the Dutch pig, but cannot cause a response to GP strain 13 . This fully demonstrates the individual's genetic control of the immune response. In the 1970s, McDevitt and others used artificial antigens to find in vivo immune loci that control immune responses (immuneresponslocus) located in the H-2 complex in the region I, called this gene as immune response gene-1 (immune uesponse , Ir-1).

Immunogenic immune adjuvant

The substances of the immune adjuvant are: microorganisms and their products, commonly used microorganisms are mycobacteria, corynebacterium pumilus, pertussis, and levodolan-negative bacillus, lipopolysaccharides, and muramyl disulfide from mycobacterium Peptides, etc. Polynucleotides, such as polyinosinic acid: cytidylic acid (poly1: C), polyadenylic acid (poly1: A: ), etc. Freundadjuvant, which is currently the most commonly used adjuvant in animal experiments, it is the same amount of antigen aqueous solution and oil (paraffin oil or vegetable oil) mixed with emulsifier (lanolin or leaf Tween) 80) A water-in-oil antigen emulsion is made, which is called incomplete Freund's adjuvant. Adding mycobacteria (such as dead card vaccine) to incomplete adjuvant is called complete Freund's adjuvant. Inorganic substances, such as alum and aluminum hydride.

The mechanism of action of adjuvants is not completely clear: it may increase the surface area of the antigen and is easily swallowed by macrophages; extend the retention period of the antigen in the body and increase the chance of contact with immune cells; The local lymph node inflammatory response is conducive to stimulating the proliferation of immune cells.