免疫学英文名词解释（一）
1. Immunity: “a condition of being able to resist a particular disease especially through preventing development of a pathogenic microorganism or by counteracting the effects of its products”
2. Immunology: Immunology is the study of our protection from foreign macromolecules or invading organisms and our responses to them.
3. Innate immunity: evolves with the germline and involves receptors, enzymes and cells that detect conserved aspects of microbes and parasites. It is the 1st line of defense. No specificity, no memory.
4. Adaptive immunity is provided by T & B lymphocytes. It is the 2nd line of defense. It has two important characteristics: Immune response is highly specific for the antigen that triggered it. Exposure to antigen creates an immunologic “memory.”
5. Primary lymphoid organs: Lymphoid organs include primary (bone marrow & thymus) and secondary lymphoid organs and tissues (lymphoid nodes、spleen、MALT). Primary lymphoid organs are the place where lymphocytes develop and mature. Lymphocytes includes B cell and T cell, respectively originating from bone marrow and thymus and mediates humoral and cellular immunity.react to中文
6. Secondary lymphoid organs: Secondary lymphoid organs are the place that immune responses happen, which include lymph nodes, spleen, tonsil and MALT. Lymph nodes drain the connective tissues of the body. The spleen drains the blood. MALT are responsible for local infection.
7. MALT: The majority (50%) of lymphoid tissue in the human body is located within the lining of the major tracts, including respiratory, digestive and genitourinary tracts. This is because these are the main sites of entry for microbes into the body. These are collectively called the mucosa-associated lymphoid tissues (MALT).
8. Antigens are molecules which are recognized by receptors on lymphocytes. B lymphocytes usually recognize intact antigen molecules, while T lymphocytes recognize antigen fragments on the surface of antigen presenting cells.
9. Epitope:Antigen molecules each have a set of antigenic determinants, also called epitopes. Epitopes are molecular shapes recognized by antibodies and T cells of the adaptive immune system.
10. Clonal selection: Each lymphocyte is genetically programmed to be capable of recognizing essentially only one particular antigen. When an antigen binds to the cell that can recognize it, it is induced to proliferate rapidly. Within a few days there are a sufficient number to mount an adequate im
mune response. In another words, the antigen selects for and generates the specific clones of its own antigen-binding cells, a process called clone selection. In brief: clone selection involves recognition of antigen by a particular lymphocyte, this lead to clonal expansion and differentiation to effector and memory cells
11. Opsonization: This s is a process of making a microbe easier to phagocyte. A number of molecules called “opsonins” do this by coating the microbes and aid attachment of the microbe to the phagocyte and also trigger activation of phagocytosis. Opsonins include the complement component C3b and antibody which acting as a bridge between antigen and phagocytes.
12. NK cells: belong to lymphocyte family. But in contrast to all T and B lymphocytes, NK cell do not express antigen-specific receptors and do not possess the adaptive property of memory cell development: they are there for considered to form part of the innate immune system. However, like Tc, their main function is to kill infected cell and tumor cells using similar mechanism to those of Tc cells to induce apoptosis of their targets. NK cell are also able to kill targets coated with IgG via their receptor for IgG. This property is referred to as ADCC.
13. DCs are required by T cell to enable them to respond to antigens. DCs are most important antigen
presenting cells known so far and are the interface of innate and adoptive immunity. Functions: Antigen up-taking in peripheral sites & antigen presentation in lymph nodes.
14. Complement: The complement system is an important component of innate immunity It can be activated by the classical and alternative pathways, both pathways will eventually lead to the lytic pathway which featured by the formation of MAC.
Function of complement: anaphylaxis (C3a,C5a), chemotaxis (C5a)，opsonization (C3b,C4b), lysis (C56789)
15. Interferons: Interferons are proteins involved in protection against viral infections. The two kinds of interferon, type I and type II, have different cellular origins and mediate a range of different activities. They interfere with viral replication but also are signaling molecules between cells.
16. lymphocyte traffic and recirculation Lymphocytes produced in the primary lymphoid organs (thymus-T, bone marrow-B) migrate via the bloodstream to the secondary lymphoid organs/tissues where they carry out the function. They do not stay in one site but continually recirculate through the body in search of antigens.
17. Affinity is the tightness of binding of an antibody binding site to an antigenic determinant (epitope)----the tighter the binding, the less likely the antibody is to dissociate from antigen.
18. Valence: Valence is the maximum number of epitopes with which the antibody can react.
19. Avidity: antibody binds a multivalent antigen is termed avidity, to differentiate it from the affinity of a single antigenic determinant for an individual combining site. Antibody avidity indicates the overall strength of interaction between antibody and antigen.
20. Isotype: These are genetic markers on immunoglobulins shared by all the individual of same species. The genes for isotypic variants are present in all healthy members of a species. For example, the genes for γ1, γ2,γ3, γ4, μ, α1, α2, δ, ε, κ and λ chains are all present in the human genome, and are therefore isotypes.
21. Allotype:These are genetic markers on immunoglobulins that segregate within the species. This refers to genetic variation between individuals within a species. For example, the variant of IgG3 called G3m(b0) is characterized by a phenylalanine at position 436 of the γ3 heavy chain. It is not found in all people and is therefore an allotype. Allotypes occur mostly as variants of heavy chain constant regions.
22. Idiotype: These are unique antigenic determinant associated with antigen binding sites of antibodies and are the results of the different amino acid sequences which determine their specificities. Variation in the variable domain, particularly the hypervariable regions, produces idiotypes. These determine the binding specificity of the antigen-binding site.
23. CDRs: At the amino acid level, the variable region of antibody is comprised of three regions of extreme variability (hyervarible region). They are called complementarity-determining regions, or CDRs.
24. FRs: Interspersed among the CDRs are framework regions (FRs) which are less variable and more evolutionarily conserved. At the three-dimensional level, the three CDRs of each chain converge to form a combining site which recognize the antigenic determinant (epitope).
25. Monoclonal antibody: In 1975, Kohler and Milstein developed a procedure to create cell lines producing predetermined, monospecific and monoclonal antibodies. The basic technology involves fusion of an immortal cell (a myeloma tumor cell) with a specific predetermined antibody-producing B cell from immunized animals or humans. The resulting hybridoma cell is immortal and synthesizes homogeneous, specific, mAb which can be made in large quantities.
26. ADCC：ANTIBODY-DEPENDENT CELL-MEDIATED CYTOTOXICITY –The linking of antibody bound to target cells (virus infected cells, or some tumor cells) with FcR of natural killer cells (NK cells), neutrophils, macrophages,or eosinophils can result in killing of the target cell.
27. cytokines: Definition: Cytokines are small molecules, secreted by cells in response to a stimulus. Function: As a group, cytokines induce growth, differentiation, chemotaxis, activation and/or enhanced cytotoxity. They are used for strengthening communications between cells.
28. Toll like receptors (TLR)
Toll like receptors are a family of proteins of which there are at least 5 known members.
Using TLRs, innate immune cells can detect and respond to infection by recognizing conserved motifs of microbes. TLRs transmit signals about microbial constituents to the nucleus, thus regulating the type of genes expressed, and the subsequent response.

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