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MindMap Gallery food immunology
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food immunology
This is a mind map about food immunology. Food immunology is a basic subject that studies the principles and applications of human immune phenomena. It is also an applied subject closely related to food reality.
Edited at 2024-11-28 17:14:14- È sufficiente leggere in questo modo Capitolo 5 Creazione di tre dimensioni della capacità di apprendimento
Questo è il capitolo 5 del libro dell'insegnante Zhao Zhou "Questo è abbastanza da leggere", che parla principalmente di questi aspetti: ① L'importanza dell'abilità di apprendimento ② Come aggiungere contesto alle informazioni ③ Come distinguere la conoscenza e le informazioni Non mi affretta a mettere in discussione e sfidare ⑤Come usare note appiccicose per aggiornare la capacità di apprendimento ⑥ Perché inseguire i "merci secche" uno pseudo-apprendimento?
- Collezione dell'utente di DeepSeek
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- DeepSeek 30 Istruzioni di alimentazione
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food immunology
- È sufficiente leggere in questo modo Capitolo 5 Creazione di tre dimensioni della capacità di apprendimento
Questo è il capitolo 5 del libro dell'insegnante Zhao Zhou "Questo è abbastanza da leggere", che parla principalmente di questi aspetti: ① L'importanza dell'abilità di apprendimento ② Come aggiungere contesto alle informazioni ③ Come distinguere la conoscenza e le informazioni Non mi affretta a mettere in discussione e sfidare ⑤Come usare note appiccicose per aggiornare la capacità di apprendimento ⑥ Perché inseguire i "merci secche" uno pseudo-apprendimento?
- Collezione dell'utente di DeepSeek
Per aiutare tutti a usare DeepSeek in modo più efficiente, è stata compilata una raccolta di Map Mind Mind Guide DeepSeek! Questa mappa mentale riassume il contenuto principale: collegamenti correlati a Yitu, analisi del profilo DS, confronto tra rotte tecnologiche DeepSeek e Chatgpt, Guida di distribuzione del modello DeepSeek e Qwen, come fare più soldi con DeepSeek, come giocare a DeepSeek, DeepSeek Scientific Research Application Aspetta, permettendoti di cogliere rapidamente l'essenza dell'interazione AI. Che si tratti di creazione di contenuti, pianificazione del piano, generazione di codice o miglioramento dell'apprendimento, DeepSeek può aiutarti a ottenere il doppio del risultato con metà dello sforzo!
- DeepSeek 30 Istruzioni di alimentazione
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food immunology
introduction
Basic content of immunology
The nature and function of immunity
Essence: The body's identification of "self" or "non-self" substances and the elimination of various reactivity of non-self substances
Function: immune defense, immune stability, immune surveillance
Types and Characteristics of Immune Responses
Immune response refers to the entire process in which immune active cells recognize antigen molecules, activate themselves (or lose their activation potential), proliferate, differentiate and produce effects.
type
Non-specific immune response is also called innate immune response. The body's ability to respond to non-self antigenic substances is innate. This characteristic, also known as natural immunity or innate immunity, is an immune defense mechanism that always exists in the body.
Specific immune response is also called adaptive immune response. The body's ability to respond to non-self antigenic substances is acquired and acquired when the body comes into contact with foreign antigens. This characteristic is also called acquired immunity or adaptive immunity.
Characteristics of specific immune responses
Specificity, adaptability, the ability to identify "self" and "not oneself", memory, self-regulation characteristics
The composition and function of the immune system
immune organ
Center: It is the place where immune cells occur, differentiate, screen and mature. It includes bone marrow, thymus and supracoelal bursa
Periphery: It is the place where immune cells settle and proliferate. It is also the place where immune cells receive antigen stimulation to produce immune responses such as specific antibodies and sensitized lymphocytes. It includes lymph nodes, spleen, tonsils, skin and mucosal lymphoid-related tissues, etc.
immune cells
Lymphocytes include T lymphocytes and B lymphocytes. Because T cells and B cells can specifically recognize antigens with TCR (Tcell receptor, T cell receptor) and BCR (Bcell receptor, B cell receptor), they are also called antigen specificity. Lymphocytes. They mediate cellular immunity and humoral immunity respectively.
Antigen-presenting cells (APC cells) include dendritic cells, giant cells, etc. Cells that can capture, process and present antigens play an important role in antigen presentation and immune regulation in the immune response process.
Phagocytes include monocytes-macrophages and neutrophils. It has phagocytic and bactericidal functions and plays an important role in innate immunity.
Natural killer cells, namely NK cells, can spontaneously kill virus-infected cells and tumor cells and play an important role in innate immunity.
Immune molecules can be divided into membrane molecules and secretory molecules according to their state of existence.
Antigens and Antibodies and Immune Response Applications
Antigen): refers to a substance that can bind to TRC/BCR or antibodies and has the potential to initiate an immune response. Simply put, it can induce the body to produce humoral immunity and cellular immune responses.
Antibodies: B cells differentiate into plasma cells under effective antigen stimulation and produce immunoglobulins that specifically bind to the corresponding antigens. This type of immunoglobulins is called an antibody.
Development and Application of Immunology
The establishment and development of immunology
Classical Immunology Era
Modern and Modern Immunology Era
Applications of Immunology
Immunology and Medicine and Biology
Immunology and Medical Biotechnology
Immunology technology has broad application prospects
Immunology and Food Science
Food nutrition and health food and human immunity
Foodborne Disease and Food Immunology
Immunotechnology and food analysis and testing
immune system
immune organ
central immune organ
The central immune organ includes the thymus and bone marrow in humans and mammals, and the cavity or bursa of Fabricius in birds. It is the place where various types of immune cells occur, differentiate and mature.
Bone marrow is a hematopoietic organ and the place where various immune cells occur and differentiate. It is the place where B cells differentiate and mature. It is also the main place where secondary humoral immune responses occur.
Thymus
Located in the upper part of the chest, behind the sternum, the thymus is divided into left and right lobes. Its basic structural unit is the thymic lobule, which is divided into cortex and medulla. Thymic parenchyma is composed of thymocytes and stromal cells.
Function ① Cultivate and export mature T cells ② Produce thymus hormone
The supracavitary bursa, also known as the bursa of Fabricius, is a blind sac-like tissue on the dorsal side of the cloaca of birds. Its structure is similar to that of the thymus. It has a capsule and is also divided into two parts: the cortex and the medulla.
peripheral immune organs
Lymph nodes
It is mainly distributed in the non-mucosal parts and is located at the intersection of lymphatic vessels throughout the body. It is similar in size to a soybean, has a membrane, and can be divided into two parts: the cortex and the medulla.
Function ① Filter and remove foreign matter ② Generate immune response
spleen
The spleen is located in the upper left side of the abdominal cavity and is the largest immune organ in the body. The adult spleen weighs 150~200g and is rich in blood vessels. It is surrounded by a capsule and is divided into two parts: the cortex (white pulp) and the medulla (red).
Function: ① Hemofiltration ② Produce immune response ③ Produce phagocytosis enhancing hormone
Mucosal and cutaneous immune system
It is the first part of the body to receive stimulation from foreign antigens, the first line of immune defense and the main site where immune responses occur. The total number of immune cells in it may be greater than the number distributed in lymphoid organs. Plays an important role in stimulating systemic and local immune responses.
The skin immune system is the site where the body's immune response is stimulated against transdermal invasion antigens, and it is also the site where immune effects occur.
Mucosal immune system (MIS): includes mucosal lymphoid tissues such as the digestive tract, respiratory tract, and genitourinary tract. In terms of human food nutrition and immunity, mucosal immunity, mainly in the digestive tract, plays an important role.
lymphocyte recirculation
Lymphocyte recirculation refers to the repeated and periodic circulation of lymphocytes between blood and lymphoid tissue. It is a patrol activity of lymphocytes in order to capture antigens and exert effective protective effects.
The recycling of lymphocytes has obvious characteristics. First, recycling is dominated by worker cells. Second, recycling is selective.
immune cells
Lymphocytes
Lymphocytes (lymphocytes) are the main cell group that constitutes the body's immune system and are the main cells that perform immune functions.
T lymphocytes
T lymphocytes, or T cells, are the abbreviation of thymus-dependent lymphocytes (thymmus-dependent lymphocytes). Worker cells play a key role in specific immune responses. They are not only responsible for cellular immunity, but also participate in the humoral immunity of B cells. It also plays a supporting and regulating role.
T cell membrane surface molecules
Antigen receptor complex ① Worker cell antigen receptor ② CD3 ③ and protein molecule
Membrane accessory molecules ①. CD4/CD8 coreceptor ② CD28 costimulatory receptor ③ CD2-LFA-2 ④ CD45 and CD45R
Other surface molecules ① Cytokine receptors ② CD40L ③ Mitogen receptors ④ MHC molecules ⑤ Hormone and mediator receptors
T cell subsets
According to the functional characteristics of T cells, they can be divided into two categories: one is regulatory T cells, including helper T cells (Th cells) and suppressor T cells (T cells); the other is effector T cells , including killer T cells (CIL or Tc cells) and delayed hypersensitivity worker cells (or Td cells). According to different TCR types, T cells can be divided into aβ T cells and γδ T cells. aβT cells are further divided into different subpopulations based on their cell surface molecules and functions.
γδT cells
αβ T cells ① CD4* T cells ② CD8 T cells
Differentiation and development of T cells
Development of TCR The earliest T cell lineage-specific gene expressed in the thymus during differentiation and maturation of T cells is CD3δ.
Positive selection for T cell development. Thymic selection is a key process in T cell development and differentiation, which enables T cells to acquire the ability to identify themselves and non-self.
Negative selection in T cell development can remove those thymocytes that react with self-components and obtain mature T cells that are tolerant to self-components.
B lymphocytes
Differentiation and maturation of B cells: B2 cell differentiation and maturation is divided into two stages: the first stage occurs in the bone marrow and does not rely on antigen stimulation; the second stage occurs in the periphery and relies on antigen stimulation.
B cell membrane surface molecules
Antigen receptor complex_B cell antigen receptor (B cell antigen receptor, BCR) is an important basis for existing in B cells. Cell surface membrane immunoglobulin (surface membrane immunoglobulin, Smlg or mlg).
Membrane accessory molecules, membrane accessory molecules of B cells, can transmit antigen-stimulated signals during the activation process after B cells bind to antigens, and participate in the interaction between B cells and T cells. ① DCDI and CD2L synergistic complex ②) CD40-Co-stimulatory receptor ③ CD45-Protein tyrosine phosphatase
Other membrane surface molecules ① B7 (CD80) ② MHC molecules ③ Fc receptor ④) complement receptor ⑤, mitogen receptor ⑥ cytokine receptor hormone and neurotransmitter receptor
B cell subsets
(1) B1 cells, function ① produce antibacterial antibodies to play an anti-infectious role. ② Produce a variety of antibodies against self-antigens, which are related to autoimmune diseases.
(2) B2 cells, function: can produce IgG and other antibodies against foreign antigens, and are the main cells responsible for the body's humoral immune function. In addition, B2 cells also have antigen presentation and immunomodulatory functions.
(3) NK cells
Most of the NK cells belong to large granular lymphocytes (LGL) in morphology. The cytoplasm contains many azurophilic granules. These granules contain perforin that can dissolve cells and granules with serine protease activity. enzymes&ranzymes).
This type of cells does not rely on antigen stimulation and can spontaneously dissolve a variety of tumor cells and virus-infected cells. They are called natural killer cells.
Because NK cells possess FcγRIII (CD16), they can bind to and kill target cells bound by IgG, causing target cells to lyse, which is antibody-dependent cell-mediated cytotoxicity (ADCC).
There are two receptors on NK cells, one is a receptor that can stimulate its killing effect, and the other is a receptor that inhibits its killing effect.
NK cells are an important type of immune regulatory cells that regulate T cells, B cells and bone marrow stem cells, and can release cytokines. NK cells play an important role in the body's anti-viral infection and anti-tumor immunity.
Antigen presenting cells (APC)
During the immune response, a type of immune cells that can capture, process, and process antigens and present them to antigen-specific lymphocytes are called antigen-presenting cells (APCs).
The mononuclear phagocyte system (MPS) includes premonocytes in the bone marrow, monocytes in the peripheral blood, and macrophages in the tissues.
Dendritic cells (dendritiecelks, D cells), also known as D cells, are irregular in shape. Their cell membranes extend outward to form many long dendritic processes. There are no lysosomes and phagosomes in the cytoplasm, and they can survive through pinocytosis. Ingest antigenic foreign matter, or use its dendrites to capture and retain antigenic foreign matter.
The biological functions of D cells are
:①Capture antigen
②Processing antigens
③Present antigen
④Other functions: A variety of costimulatory molecules are expressed on the surface of D cells, which provide activating and fine costimulatory signals by binding to ligands on the surface of T cells. It is also involved in the growth and differentiation of lymphocytes and the body's immune surveillance function.
In the immune response, the most important characteristics of APC are that they can process ingested protein antigens and express MH class II molecules. They also express co-stimulatory molecules such as CD80 (B7) to fully activate T cells.
Other immune cells (1) Vascular endothelial cells 2) Neutrophils (3) Eosinophils (4) Basophils (5) Mast cells (6) Other blood cells
Cytokines
Cytokine overview
Cytokines (CKs) are highly active, multifunctional small molecule proteins that are an important part of the immune system, including lymphokines secreted by lymphocytes: (Iymphokine) secreted by monocytes and macrophages. Monokine and factors secreted by other cells, etc.
Common features ① They are all polypeptides or glycoproteins with molecular weight <60ku. Most are monomers, and a few are dimers or trimers. ② Usually produced by cells activated after being stimulated by antigens or mitogens. ③ Cytokines can exert their biological effects only after binding to the corresponding receptors on the surface of target cells. ④High-efficiency biological activity. ⑤A cytokine can act on a variety of cells and exert a variety of biological effects, and multiple cytokines may also produce the same or similar biological effects. ⑥Cytokines can induce and regulate each other, and their biological activities have superimposed, synergistic or antagonistic effects, showing complex network characteristics.
Types of cytokines 1. Interferons (IFNs) 2. Interleukins (ILs) 3. Colony stimulating factors (CSFs) 4. Tumor necrosis factors (TNFs) 5. Transforming growth factor (TGF-R)
Biological functions of cytokines (1) Immune mediation, anti-tumor and anti-infection effects (2) Mediation of cellular immunity and humoral immunity, regulation of T cell and B cell activation, proliferation and differentiation (3) Stimulation of bone marrow hematopoietic function (4 ) Role in inflammation, infection and endotoxemia (5) Role in allergies and autoimmune diseases
immune response
Overview
Basic concepts of immune response
Antigen substances enter the body and stimulate the immune system to undergo a series of reactions to eliminate the antigen. That is, the process in which immune cells recognize, ingest, and process antigens, and then activate, proliferate, and differentiate to produce immune effects.
immune response type
According to the effect mechanism, it is divided into
humoral immunity
Cellular immunity
According to the effect results, it is divided into
physiological immune response
pathological immune response
Basic process of immune response
humoral immune response
Antigen recognition and antigen presentation by B cells
Identification of TI-Ag
Identification and presentation of TD-Ag
B cell activation and signaling
B cell activation signals
TI antigens stimulate B cell activation - direct effect.
TD antigen stimulates B cell activation – two signals are required
cell synergy
APC interacts with Th cells
B cells interact with Th cells
The role of cytokines
Antibody-Mediated Immune Effects
Differences in B cell responses to TI-Ag and TD-Ag
Ig class conversion
General rules for antibody production
immune effects of antibodies
immune memory
Induction of B cell memory
Maintenance of memory B cell pool
Memory B cell response to re-antigen
cellular immune response
Recognition of antigens by T cells
. type
MHC I endogenous antigenic peptide
MHC II exogenous antigenic peptide
. Way
MHC – Antigenic Peptide – TCR
CD4/CD8 - MHC II/MHC I
Process (interaction between APC and T)
Activation, proliferation and differentiation of worker cells
Molecules involved in T cell activation
The first signal triad CD4/CD8CD3 intracellular segment ITAM transduces signals
Second signal CD28-B7 and other adhesion molecules (promote IL-2 synthesis)
CK IL-1 (APC), IL-2 (T), etc.
Signal transduction of T cell activation
clonal proliferation and differentiation
T cell mediated immune effects
Th1: expresses CD40L and secretes CK
Th2: expresses CD40L and secretes CK
Tc:
Tc via TCR-peptide-MHC
Antigen presentation
concentration of antigen
Antigen processing, processing and presentation by APC
Regulation of immune response
Regulation at the molecular level
Regulation at the cellular level
T cell immune regulation
Immunomodulation of other cells
B cell immune regulation
Immunomodulation of macrophages
Immunomodulation of NK cells
Regulation of the neuroendocrine system
complement system
Overview of the complement system
The components of the complement system
intrinsic complement components
complement regulatory protein
complement receptor
Nomenclature of the complement system
1) Intrinsic components involved in the classical pathway: represented by C followed by Arabic numerals, such as C1, C4, C2, etc.
2) Components involved in the alternative pathway: expressed in English capital letters, such as B factor, D factor, P factor, H factor, etc.
3) Regulatory components: named after their functions, such as C1 inhibitor, C4 binding protein
4) Cleavage fragments: small fragments are represented by a, such as C3a; large fragments are represented by b, such as C3b.
5) Enzyme active ingredient: draw a horizontal line through the symbol, such as C3bBb.
Physicochemical properties of complement components
Activation regulation and biological effects of complement system
Classical Activation Pathway (or Traditional Pathway)
1 Antigen-antibody specific binding and activation
2 The reaction sequence is C1qrs-C4-C2-C3-C5-C6-C7-C8-C9
3 Produce 3 convertases: C1 esterase, C3 convertase, C5 convertase
4 Produce 3 anaphylatoxins (Anaphylatoxin), C3a, C4a,C5a
Lectin pathway of complement activation
Alternative activation pathway (or alternative pathway)
Formation of the membrane attack complex
Comparison of three pathways of complement activation
Regulation of complement system activation
(1) Regulation of complement’s own decay
(2) The role of soluble complement regulatory factors
(3) The role of membrane complement regulatory proteins and complement receptors
The biological role of the complement system
1. Complement-mediated cell lysis
2. Biological effects mediated by complement activation fragments
3. Remove apoptotic cells
4. Role of inflammatory mediators
The nature and function of immunity
Structure and function of MHC genes and HLA molecules
MHC genetic makeup
MHC: It is a group of closely linked genes (classes I, II, III) that encode major histocompatibility antigens on a certain chromosome of vertebrates, control mutual recognition between immune cells, and regulate the body's immune response.
The structure of the HLA molecule
The HLA complex is located on the short arm of human chromosome 6 and has 224 loci. From the centromere side, they are class II genes, class III genes and class I genes.
Distribution of HLA antigens
Biological functions of HLA
Process and present antigen
Start and regulate immune response
Inducing T cell maturation—formation of a functional T cell library
Antibody
Antibody structure and function
Antibody (Ab) is an immune molecule produced by the body after being stimulated by an antigen that can specifically recognize, bind and clear the antigen. It is a globulin with immune function produced by the B cell line after recognizing the antigen, proliferating and differentiating into plasma cells.
Basic structure of antibodies
1. Heavy chain Each heavy chain consists of 450~550 amino acid residues and has a molecular mass of 55~75ku.
2. Light chain Each light chain is about 1/2 of the heavy chain, consists of about 214 amino acids, and has a molecular mass of about 25ku.
3. Other structures (1) J chain joining chain, J) (2) Secretory piece
variable and constant regions
The part in the Y region where the composition and arrangement of amino acids change most drastically is called the hypervariable region (HVR.).
In the 1/2 of the Ig proximal C-terminal working chain and the 3/4 (or 4/5) region of the H chain, the amino acid composition is relatively stable in the same type of Ig of the same species, which is called the constant region.
Functional regions of antibodies and their functions
1. Functional area of variable area
2. Each functional area in the constant region
(1) CH1, CL
(2) CH2 of IgG, and CH3 of IgM
(3) CH3/CH4
Hydrolyzed fragments of Ig
1 Hydrolysis of papain: Papain cuts Ig near the N-terminus of the disulfide bond between heavy chains in the hinge region, forming three hydrolysis fragments: two identical fragments of antigen-binding, referred to as Fab Segment, equivalent to the two arms of an antibody; a crystallizable fragment (referred to as the Fc segment).
2. Hydrolysis of pepsin: Pepsin (pepsin) can break the Ig near the C-terminus of the disulfide bond between the heavy chains in the hinge region to obtain an F (ab22 fragment and inactive biologically active F (ab22 fragment) that has antibody activity and bivalently binds to the antigen. Small molecule peptide fragments
Antigenicity of the antibody
1./Isotype (isotype) and secondary antibody: Isotype refers to the antigen specificity of I5 shared by all individuals of the same species.
2. Allotype: Allotype refers to the 1g antigenic difference between different individuals within the same species.
3. Idiotype: The antigen specificity of the Ig V regions produced by different B cell clones in the body is different. Each hypervariable region has a unique antigenic determinant structure, which is called the antibody's idiotype.
Classification of antibodies and their biological functions
Functions and characteristics of five types of antibody molecules
1. Functions and characteristics of IgG: IgG is the main anti-infectious antibody with antibacterial, antiviral, toxin neutralizing and immunomodulatory effects. It activates complement through the classical pathway.
2. Functions and characteristics of IgM: It has the largest molecular mass. IgM is the earliest Ig synthesized and secreted in individual development (starting to be synthesized in the late embryonic period). The human body’s natural blood type antibodies are IgM antibodies.
3. Functions and characteristics of IgA: IgA can effectively agglutinate bacteria and neutralize toxins, but cannot pass through the placenta. IgA can neutralize viruses, prevent food proteins from entering the blood, and plays an important role in the treatment of food overlock.
4. Functions and characteristics of IgD: It cannot pass through the placenta and cannot activate complement. It is often expressed on the surface of B cells in monomeric form and is not expressed by immature B cells. Therefore, it is generally believed that IgD is related to the maturation of B cells and plays a certain role in preventing the occurrence of immune tolerance.
5. Functions and characteristics of IgE: It has certain significance in fighting parasitic infections. IgE is also the main antibody that mediates food allergy, causing type I hypersensitivity reactions.
Biological functions of antibodies
1. Activate complement
Binds to cellular Fc receptors
1) Regulating phagocytosis
2) Exert antibody-dependent cell-mediated cytotoxicity
3), mediates type I hypersensitivity reaction
Crosses the placenta and mucous membranes
Binds bacterial proteins
Antibody genes and expression
Antibody genes and expression
Gene library and gene structure of human antibodies
Rearrangement of antibody genes
1) Ig heavy chain VDJ gene rearrangement
(2) Ig light chain VJ gene rearrangement
Other properties of antibody expression
1) Cutting difference and category conversion
(2) Allele rejection and isotype rejection
(3) Membrane immunoglobulin and secretory immunoglobulin
Antibody Diversity and Polyclonal Antibodies
The mechanism of antibody diversity
① Ig is controlled by multiple genes. H and L each have specific coding gene libraries that store a large number of gene fragments.
② The random combination of vD-J and v-J connections and the base mutations, shifts and insertions of these connection sites make the number of V regions extremely large.
③ The class switching of Ig and the random combination of H and L chains at the protein level double the specific types of antibodies.
④ After antigen stimulation, high-frequency gene mutations in somatic cells,
⑤ Different Ig molecules have membrane type and secretory type with certain differences in structure.
Clonal selection theory of antibody production
Polyclonal antibodies vs monoclonal antibodies
The antibodies in the serum produced by immunizing animals with antigens are a heterogeneous mixture of multiple antibodies. Such antibodies are called polyclonal antibodies.
Monoclonal antibodies are homogeneous antibodies produced by the proliferation of hybridoma cells obtained by hybridizing a single B cell with a tumor cell. They only bind to one antigenic determinant.
Introduction to other Ig
Introduction to other mammals
Immunoglobulin in milk
1. Characterization of immunoglobulins in human milk
2. Milk immune globulin
Introduction to poultry Ig
antigen
Basic concepts of antigens
Immunogenicity and immunoreactivity of antigens
The immunogenicity of an antigen refers to the property of a substance that stimulates the body to produce an immune response and induces the production of antibodies or effector lymphocytes.
Immunoreactivity refers to the specific binding characteristics of a substance (antigen) to an antibody, also known as specific reactivity.
(Complete antigen) A substance that is immunogenic and has specific reactivity. Most protein antigens fall into this category.
A hapten or incomplete antigen is a substance that can react with the corresponding specific antibody but does not itself induce the formation of antibodies.
Physicochemical characteristics and classification of antigens
Physical and chemical properties of antigenic substances
Foreign matter (1) Foreign substance (2) Allogeneic substance (3) Exposure of self-mutated components or hidden components
Molecular size: The immunogenicity of an antigen is closely related to the size of the antigen molecule. The larger the molecular mass, the stronger the immunogenicity.
Chemical structure and composition: Antigenic substances must have a relatively complex chemical composition and structure. Generally speaking, protein substances have strong antigenicity, and antigens containing aromatic amino acids (especially tyrosine) are highly immunogenic. The side chains in the molecular structure have stronger immunogenicity than similar substances without side chains.
Molecular conformation and accessibility
Molecular conformation refers to the three-dimensional structure of some special chemical groups in an antigen molecule. It determines whether the molecule can match the antigen receptor of lymphocytes and thereby initiate an immune response.
Accessibility refers to the ease with which the special chemical groups of the antigen molecule come into contact with the corresponding antigen receptors on the surface of lymphocytes.
physical state
Generally, proteins in the aggregated state are more immunogenic than their monomers.
Particulate antigens are more immunogenic than soluble antigens.
Antigen integrity
Classification of antigens
Classification based on whether T cell assistance is required to induce an immune response
(1) Thymus-dependent antigen
(2)Thymus-independent antigen
Classification based on antigen source
(1) Natural antigen
① Cells, bacteria and viruses ② Proteins ③ Polysaccharide antigens ④ Lipid antigens ⑤ Nucleic acid antigens
Natural antigens can be divided into: ① xenoantigens ② alloantigens ③ autoantigens ④ heteroantigens according to their close relationship with the host
(2) Artificial antigen mainly refers to the complete antigen formed by connecting small molecule hapten to a certain carrier.
(3) Synthetic antigens are molecules with antigenic properties that are chemically synthesized. Mainly synthetic amino acid polymers with branched or linear chains.
(4)Superantigen
Immunological Characteristics of Antigens
Antigen specificity and antigenic determinants
(1) Antigen specificity is the most important feature in the immune process and is also the theoretical basis for immunological detection, diagnosis, and prevention.
(2) Antigenic determinants and their categories
An antigenic determinant (also known as an epitope) is a specific chemical structure in an antigen molecule that can specifically bind to an antibody or can be specifically recognized by an antigen receptor on the surface of lymphocytes (including chemical groups and molecular conformation).
Structurally speaking, antigenic determinants are divided into two categories: conformational determinants and sequential determinants.
(3) Antigenic valence The binding valence of an antigen refers to the total number of antigenic determinants on the surface of the antigen molecule that can bind to the antibody molecule.
Immunological Characteristics of Haptens
(1) Characteristics of hapten Hapten must be coupled to a certain carrier to exhibit immunogenicity.
(2) Carrier effect. Different carriers have different immunogenicity after being connected to the same hapten. During the first and second immunization, only when the hapten is combined with the same carrier can an obvious anti-hapten effect be produced. Antibodies, this is now called the carrier effect.
(3) Specificity of hapten: The antibody obtained by converting the hapten into a complete antigen-immunized animal has a strong specific response to the simple hapten.
Class properties of antigens (cross-talk)
Two antigens from different sources have common antigenic determinants or similar antigenic determinants. The antibodies produced by the determinants stimulated by the body can react with the two antigens, which is called cross-reaction (crossTeaction). Two antigens with common antigenic determinants are called common antigens.
infectious antigen
bacteria
1. Somatic antigen
2. flagellar antigens and pilus antigens
3. Surface antigen
4. Bacterial toxins
5. Bacterial protective antigens
Virus
Viruses are a type of non-cellular life unit with nucleic acid (DNA or RNA) as the core and protein as the outer shell. They can only multiply within cells. According to the host they infect, they can be divided into animal viruses, plant viruses and bacterial viruses (phages).
1. Structure of viruses
2. Antigenicity of the virus
3. Virus infection route
Superantigens and immune adjuvants
superantigen
There are two main types of superantigens: exogenous superantigens (bacterial type) and endogenous superantigens (viral type).
Biological significance of superantigens
①Participate in certain pathological processes
②Induce autoimmune diseases
③Induce immunosuppression and immune tolerance
④Anti-tumor effect
Immune adjuvants refer to substances that can enhance the immune response or change the type of immune response. They can prolong the residence time of antigens in the body, increase the stimulating effect of antigens, and more importantly, stimulate the reticuloendothelial system, so that the immune cells involved in the immune response can The increase in active cells promotes the interaction between T cells and B cells, thereby enhancing the body's cellular immunity to antigens and the production of antibodies.
Antigenic substances in food