Glossary of terms

Question 1

Adaptive immunity

Answer 1

Immune responses mediated by lymphocytes and their products requiring activation by innate immune mechanisms on first encounter with antigen but acting immediately on subsequent encounters

Question 2

Afferent lymphocytes

Answer 2

lymphatic vessels entering lymph nodes from tissue spaces

Question 3

Affinity

Answer 3

The strength of a noncovalent binding reaction; the higher the affinity, the more likely two partners will exist in a complex

Question 4

Alveolar macrophages

Answer 4

Macrophages in the lung

Question 5

Antibodies

Answer 5

Highly variable proteins produced by B lymphocytes of the immune system and that recognise the antigen and target it for destruction

Question 6

Antibody-dependent cellular cytotoxicity (ADCC)

Answer 6

A process whereby FcR-bearing cells encounter an antibody-coated target cell and degranulate, releasing contents that kill the antibody-coated cell

Question 7

Antigen

Answer 7

Any molecule or part of a molecule recognised by the variable antigen receptor of the lymphocytes

Question 8

Antigenic-drift (of influenza virus)

Answer 8

Point mutations, predominantly in hemagglutinin and neuraminidase, that affect recognition by neutralizing human antibodies. Antigenic drift gives rise to pandemic outbreaks

Question 9

Hemagglutination

Answer 9

Refers to glycoproteins which cause red blood cells to agglutinate. This process is called hemagglutination. Antibodies and lectins are commonly known hemagglutinins

Question 10

Neuraminidase enzymes

Answer 10

Glycoside hydrolase enzymes that cleave the glycosidic linkages of neuraminic acids.

Question 11

Antigenic-shift (of influenza virus)

Answer 11

The reassortment of independent RNA segments from two different influenza genomes to generate a recombinant virus with new antigenic subtypes. Antigenic-shift gives rise to pandemic outbreaks

Question 12

Antigenic variation (in parasites)

Answer 12

Clonal expression of members of proteins among parasite progeny; examples include the major surface glycoproteins of trypanosomes and the red cell adhesins encoded by malaria parasites; variant expression allows parasites to evade immune recognition

Question 13

Antigen presentation

Answer 13

The binding of fragments of intracellular molecules, usually peptides derived from proteins of pathogens, by major histocompatibility complex (MHC) molecules and their presentation on the cell surface for recognition by T cells

Question 14

Antigen presenting cells

Answer 14

Cells that are capable of presenting an antigen for recognition by T cells and of activating naive T cells

Question 15

Antimicrobial peptides

Answer 15

Peptide antibodies that provide defense against microbes and viruses by interacting with membranes of infectious agents and increasing their permeability. Human antimicrobial peptides are members of either the a-defensin, β-defensin or cathelicidin families

Question 16

Attenuation (of a pathogen)

Answer 16

The loss of pathogenicity, usually through adaptation to growth in culture in adverse conditions or in cells from a species other than that of the normal host. Attenuated pathogens are the basis of many vaccines

Question 17

Avidity

Answer 17

Increased apparent affinity of a molecule for its ligand due to the presence of multiple binding sites on both partners

Question 18

Basophils

Answer 18

Circulating myeloid lineage cells that are characterized by cytoplasmic granules that stain with basic dyes and contain inflammatory mediators and are believed to be important in defense against parasites as well as in inflammatory and allergic reactions

Question 19

C1q

Answer 19

Complement component that binds to antibodies in immune complexes and activates the classical pathway of compliment activation. In addition to activating the compliment cascade, C1q is recognised by a pathogenic receptor of macrophages (C1qRp), and so can mediate phagocytosis directly

Question 20

C3 convertase

Answer 20

Either of two proteolytic enzymes of the compliment system that cleaves the C3 to generate C3a and C3b. The C3 convertase of the classical and lectin pathways is a complex of C4b and C2b, whereas the C3 convertase of the alternative pathway is a complex of C3b and Bb

Question 21

Capsular polysaccharide

Answer 21

Cell-surface polymers of repeating oligosaccharide units, usually linked through phosphodiester bonds that form a capsule on the surface of many pathogenic bacteria and protect bacterial cells from recognition by phagocytes. For this reason, the presence of a capsule is often associated with virulence

Question 22

Cathelicidin

Answer 22

A family of cationic antimicrobial peptides generated in pre-pro forms that require processing to generate the active peptide; cathelicidins contain an amino-terminal cathelin-like domain and a carboxy-terminal antimicrobial domain

Question 23

Chemokines

Answer 23

Any of a family of closely related small, basic cytokines whose main function is as chemo attractants. The name is a contraction of chemotactic cytokine

Question 24

Classical pathway

Answer 24

compliment activation pathway through which antibody-antigen complexes trigger the complement cascade. This pathway is also activates by the pentraxins

Question 25

Clonal detection

Answer 25

Elimination of potentially self-reactive lymphocytes. Immature lymphocytes undergo programmed cell death after binding to the antigen; in this way, cells that are bearing receptors that recognise self are deleted before they are capable of participating in immune responses. This is a major mechanism of immune tolerance

Question 26

Clonal expansion

Answer 26

the selective proliferation of mature naïve lymphocytes that encounter antigens. Only those lymphocytes bearing receptors specifically recognizing antigen are activated to proliferate and differentiate into effector cells

Question 27

Cluster of differentiation (CD)

Answer 27

The basis of a system for identifying cell surface molecules of immune cells by the use of antibodies and in which each molecule is given a specific number prefixed by CD to form the basis of a systematic nomenclature. The term cluster reflects the fact that each molecule is usually recognised by a group, or cluster of antibodies; and the appearance of the molecules usually reflects different differentiated states of the cell, hence differentiation. Surface marker molecules of immune cells of different types at different stages of differentiation or activation have been identified in this way and can be used to classify cells, or to follow their progression through development or their activation status

Question 28

Collectin

Answer 28

any of a family or structurally related, carbohydrate-recognizing proteins of innate immunity, including mannose-binding lectin and surfactant proteins A and D

Question 29

Complement

Answer 29

Serum proteins activated directly or indirectly by conserved surface features of microorganisms, or by antibody, to destroy microorganisms or induce their destruction through a coordinated immune response including induction of inflammation, attraction of leukocytes, stimulation of phagocytosis and stimulation of antibody production

Question 30

Complementarity-determining region (CDR)

Answer 30

A region of a lymphocyte receptor for antigen that participates in the antigen-binding site and determines its structural complementarity to the antigen

Question 31

Constant (C) domain

Answer 31

Ig-like domain of the type found in Ig constant regions. Constant region (C region): region of lymphocyte receptor for antigen that does not participate in antigen binding and does not vary between cells of different antigen specificity

Question 32

Coreceptor (of T lymphocytes)

Answer 32

A receptor on a T cell that recognises invariant parts of MHC molecules and forms a recognition complex with the antigen receptor and contributes to the intracellular signaling

Question 33

Corticosteroids

Answer 33

Natural and synthetic hormones that bind to and activate the glucocorticoid receptor. Corticosteroids are very effective anti-inflammatory drugs and are also immunosuppressive