Glossary

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

alveolar macrophages

Answer 3

macrophages in the lungs

Question 4

antibodies

Answer 4

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

Question 5

Antibody-dependent cellular cytotoxicity (ADCG):

Answer 5

a process whereby FcR-bearing celts encounter an antibody-coated target cell and degranulate, releasing contents that kill the antibody-coated cell.

Question 6

antigen

Answer 6

any molecule or part of a molecule recognised by the variable antigen receptors of the lymphocytes

Question 7

antigenic drift

Answer 7

(of influenza virus) point mutations, predominantly in hemagglutinin and neuraminidase, that affect recognition by neutralizing human antibodies. Antigenic drift gives rise to epidemic infections.

Question 8

shift

Answer 8

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

Question 9

antigenic variation

Answer 9

(in parasites) 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 10

antigen presentation

Answer 10

the binding of fragments of intracellular molecules, usually peptides derived from proteins of pathogens, by MHC molecules and their presentation the cell surface for recognition by T cells

Question 11

APC

Answer 11

cells capable of displaying antigen for recognition by T-celts and of activating naive T cells

Question 12

Antimicrobial peptides:

Answer 12

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 u-defensin, $defensin or cathelicidin families

Question 13

Attenuation

Answer 13

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

Question 14

avidity

Answer 14

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

Question 15

basophils

Answer 15

circulating myeloid lineage cells that-are characterised by cytoplasmic granules that stain with basic dyes and contain inflammatory mediators and are believed to be important in defence against parasites as well as in inflammatory and allergic reactions

Question 16

C1q

Answer 16

complement component that binds to antibodies in immune complexes and activates the classical pathway of complement activation. ln addition to activating the complement cascade, Clq is recognised by a phagocytic receptor of macrophages (C1qRp), and so can mediate phagocytosis directly

Question 17

C3 convertase

Answer 17

either of two proteolytic enzymes of the complement system that cleave 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 18

Capsular polysaccharide:

Answer 18

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 19

Cathelicidins

Answer 19

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 20

chemokine

Answer 20

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

Question 21

classical pathway

Answer 21

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

Question 22

clonal detection

Answer 22

elimination of potentially self-reactive lymphocytes. lmmature tymphocytes undergo programmed cell death after binding to 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 23

clonal expansion

Answer 23

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

Question 24

clonal selection

Answer 24

the process whereby potentially self-reactive lymphocytes are eliminated during ontogeny whereas mature lymphocytes recognising non-self antigens are selectively expanded

Question 25

Cluster of differential (CD)

Answer 25

the basis of a system for identifoing cell surface molecutes of immune cells by the use of antibodies and in which each molecule is given a speciflc 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 and at different stages of differentiation or activation have been identified in this way and can be used to classifiT cells, or,to follow their progress through development or their activation status.

Question 26

collectin

Answer 26

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

Question 27

complement

Answer 27

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, aftraction of leukocytes, stimulation of phagocytosis and stimulation of antibody production

Question 28

Complementarity-determining region (CDR):

Answer 28

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

Question 29

Constant (C) domain:

Answer 29

lg like domain of the type found in lg constant regions

Question 30

Constant region (C region):

Answer 30

region of lymphocyte receptor for antigen that does not participate in antigen binding and does not vary between cells of different antigen specificities

Question 31

coreceptor: (of T lymphocytes)

Answer 31

(of T lymphocytes) receptor on a T-cell that recognises invariant parts of MHC molecules and forms a recognition complex with the antigen receptor and contributes to intracellular signalling.

Question 32

Corticosteroids:

Answer 32

natural and synthetic hormones that bind to and activate the glucocorticoid receptor. Corticosteroids are very effective antiinflammatory drugs and are also immunosuppressive.

Question 33

C-type lectin

Answer 33

ell-surface or secreted protein that is characterised by a conserved three-dimensional fold and somewhat conserved amino-acid sequence and that binds to carbohydrate ligands, typically in a calcium-dependent manner.

Question 34

C-type lectern receptor

Answer 34

cell-surface proteins containing C-type lectin domains that do not bind carbohydrate ligands and are thus distinct from Ctype lectin receptors; C-type lectin receptors commonly mediate phagocytic or endocytic uptake and/or signalling into the cell

Question 35

Cytokine

Answer 35

polypeptide signalling molecules that participates in immune responses. Cytokines often act locally (in an autocrine or a paracrine manner) but can act systemically. Most cytokines are secreted molecules, but membrane-bound versions also occur in most cytokine types

Question 36

cytotoxic T cell

Answer 36

T lymphocytes specialised to kill cells infected with pathogens that replicate in the cytoplasm

Question 37

Dectin-1

Answer 37

a phagocytic C-type lectin receptor recognising microbial B-glucan polysacch

Question 38

defensins

Answer 38

any of a family of cationic antimicrobial peptides of vertebrates with three disutfide bonds and a largely beta-sheet structure.

Question 39

dendritic cells

Answer 39

specialised cells that ingest debris and infectious agents in the peripheral tissues and migrate to lymphoid tissues where they present fragments of the ingested particles for recognition by T lymphocytes in the activation of adaptive immune responses. Some dendritic cells are resident in ihe lymphoid tissues and function as phagocytes there before differentiating into antigen-presenting cells

Question 40

effector cells

Answer 40

cells that are quipped to activate or destroy other cells directly

Question 41

ELIZA

Answer 41

a technique for measuring the amount of a molecule in a sample in which the antigen is put or trapped on a solid support and then an antibody with an attached enzyme is used to bind to the trapped antigen. Alternatively, an ELISA can be used to measure the amount of a specific antibody in a sample. The amount of enzymatic activity is direcfly related to the amount of the antigen or antibody on the plate

Question 42

Eosinophils

Answer 42

cells containing cytoplasmic granules that stain with a dye eosin and contain inflammatory mediators that are released on activation by T cells or antibody-coated parasites

Question 43

epitope

Answer 43

molecular feature of an antigen that is specifically recognised by a lymphocyte or an antibody.

Question 44

Fab fragment

Answer 44

fragment of an antibody generated

Question 45

Fc fragment

Answer 45

immunoreceptors that mediate many of the effects of antibodies. These receptors are so named because the part of the antibody molecule they recognise is called the Fc region. ic receptors mediate cellular functions such as phagocytosis, cell killing, and degranulation

Question 46

heavy chain

Answer 46

the immunoglobulin heavy chains are the larger of the two kinds of polypeptide chains in the immunoglobulin molecule. Each light chain has a variable region contributing to’the’antigen-binding site, and a constant region that mediates the effector function of the molecule.

Question 47

hemagglutination

Answer 47

the property by which antibodies binding to red blood cells cause them to agglutinate

Question 48

Hemagglutinin:

Answer 48

influenza homotrimeric envelope piotein that binds to widely distributed host-cell-surface glycoproteins and glycolipids that are modified by sialic acid additions and is required for virat entry to host.

Question 49

Hematopoietic stem cell (HSC):

Answer 49

self-renewing cellthat gives rise to all the red and white blood cells

Question 50

‘Highly pathogenic avian influenza (HPAI):

Answer 50

influenza viruses with high virulence for chickens and other birds. These viruses commonly express H5, H7, H9 hemagglutinin proteins with an expanded basic amino- acid repeat that increases the ease of proteolytic diggstion required to activate the fusion domain