Ch 18: Adaptive Specific Host Defenses

Question 1

Adaptive immunity displays specificity and memory

Answer 1

Specificity:
=> means the adaptive immune system can recognize slight differences between pathogens (more accurately between antigens)

Memory:
=> menas that the adaptive immune system changes over time, responds to the second challenge by the same pathogen more quickly but in different, better ways

Question 2

Primary response

Answer 2

the response which follows the first exposure to a pathogen of antigen

Question 3

secondary response

Answer 3

the response whihc follows further exposures to the same (specific) pathogen or antigen

Question 4

adaptive immunity depends on lymphocytes

Answer 4

B and T cells

lyphocytes can rearrange their DNA after exposure

Question 5

B lymphocytes

Answer 5

mature in the bone marrow (the bursa in birds) and secrete antibodies (Ab)

most antibodies circulate in the blood, B cells and Ab are called humoral defence

Question 6

T lymphocytes

Answer 6

mature in thymus

secrete cytokines and interleukines (Th cells) or kill virus infected cells (CTLs)

cellular defence or immunity

Question 7

Antigens (Ag)

Answer 7

An Ag is a unique biological structure found only on one type of pathogen

Question 8

Viral Ag

Answer 8

all viruses have capsids, only influenza viruses have haemagglutinin proteins in the capsid, only influenze strain A H3N3 has the type H3 haemagglutinin

Question 9

Protein Ag

Answer 9

proteins are the best Ag followed by carbs, nucleic acids, and lipids (most immunogenic)

protein Ag stimulate both humoral and cellular function

Question 10

Carbohydrate Ag

Answer 10

stimulate only humoral immunity

Question 11

Lipid and Nucleic acid Ag

Answer 11

are only antigenic if attacherd to a protein or other moleucle called a hapten

Question 12

epitope

Answer 12

the smallest part of an antigen recognized by an AB or a T cell receptor

large Ag have many epitopes

Question 13

Antibodies

Answer 13

glycoproteins produced and secreated by B cells

all antibodies are at least bivalent

5 classes// isotypes

Question 14

IgM

Answer 14

the first Ab produced

is a pentamer of IgG like structyures so has 10 heavy and 10 light chains

is the Ab of teh primary respose

food at afflutination but does not bind Ag very strongly

activates complement

some B cells become memory cells

Question 15

IgG

Answer 15

cirvulatory Ab, second type produced

bivalent, can bind two identical antigens

consistant domains interact with receptors on macrophage and neutrophils to cause opsinization and complement activation

oGG is the Ab of the secondary response

higher affinity than IgM

opsinizes, activates complement, agglutinates

Question 16

IgA

Answer 16

Ab agaisnt multicellular pathogens, also involved with allergies

secreted onto mucosal surfaces and binds pathogens there

dimer of bivalent Ab, so it has 4 heavy and 4 light chains

Question 17

IgD

Answer 17

B cell surface Ab, B cell receptor

Question 18

Antibody strucutre IgG

Answer 18

4 polypeptides, 2 heavy and 2 light chains

each chain is made up of variable and consistant domains

the variable domain from one light chain and a variable domain from one heavy chain combine to form the antigen binding site

constant domains interact with receptors on macrophage and neutrophils to cause opsinization and complement activaiton

light chains have 1 variable domain and 1 constant domain

Heavy chains have 1 variable and 3 constant domains

Question 19

B cells and antibodies

Answer 19

Ab are only produced by B cells

As B cells amture, they undergorandom genetic rearrangement in the genes for Ab
=> in the varaiable region, generates a unique specificity for each Ab

each B cell produces a unique Ab

Question 20

B cell activation

Answer 20

IgD as the B cell receptor

when the B cell is activated by binding Ag to the IgD then IgM Ab are produced and secreted

B cells require T cells to activate

Question 21

Neutralization

Answer 21

Binding of antibodies to toxins// viruses to prevent them from attaching to receptors

IgG and IgM

binding of antibodies to bacterial cells to prevent them from attaching to epithelial and other cells

binding of antibodies to viruses to prevbent them from attaching to receptors

Question 22

Opsinization

Answer 22

binding of antibodies to bacteria then macrophage can bind to the Fc or constant region of that antibody - increases phagocytosis

Question 23

Agglutinization

Answer 23

Cross-linking of viruses and bacteria through at least bivalent antibodies to form clumps or aggregates

these clumps can be filtered out of the blood and lymph by the spleen and kidneys

Question 24

Complement activaiton

Answer 24

the classic pathway of complement activation starts with antibodies binding to bacteria

MAC attack to punch holes through membranes

three ways for complement activation

Question 25

Antibody dependent cell mediated cytotoxicity

Answer 25

works against large pathogens but also your own cells antibodies bind to pathogen NK cells and macrophages bind to the Fc or constant region of the antibodies and are stimulated to release granzymes to kill the pathogen

Question 26

Two MHC classes

Answer 26

MHC I is found on all nucleated cells MHC II is found only on macrophage, DC and B cells (aka APCs) MHC protiens are found attached to the cell membrane but mostly outside the cell All MHC protiens bind antigens and present them to receptors on other cells

Question 27

MHC I proteins present antigens derived form inside the cell

Answer 27

these antigens are normally derived from host protiens so are "self" antigens NK and CTL cells recognize these as "self" and do not attack those cells When a cells is infected with a virus, or an intracellular bacteria "non-self" antigens are presented NK and CTL cells recognize these as "non-self" and attack those cells and kill them (NK cells recognize the absence of MHC I)

Question 28

MHC II protiens present antigens derived outside the cell

Answer 28

macrophage and DC phagocytoize antigens form outside the cell antigens are broken up in phagolysosomes parts of the antigens attack to MHC II and are displayed on the outside of antigen presenting cells these interact with T cells to activate them

Question 29

T cells

Answer 29

T cells produce a unique receptor TcR whihc is found on the surface of each T cell also produced by random rearrangement of TcR genes

Question 30

T cells are activated by binding Ag to the TcR

Answer 30

the antigen must be presented ot the T cell by another cell Activation is achieved by binding of the TcR to the antigen attached tot he MHC molecule macrophage and DC cells present using MHC II all other cells present Ag using MHC I

Question 31

Differentiation of T cells

Answer 31

T cells differentiate into T helper cells and CTLs Th cells differentiate into Th1 and Th2 and Th17 cells Th1 activate CTLs Th2 activate B cells CTLs when activated recognize virus and bacteria infected cells through MHC I and attack and kill them

Question 32

which portion of the antibody does the NK cell bind to

Answer 32

Fc antibody bind to cell, NK cell recognizes, and kills the antibody bound cell

Question 33

Active immunity

Answer 33

creating your own immunity or activation of your own immune system because you actually got the infection

Question 34

passive immunity

Answer 34

cells and antibodies that were created in somebody elses active immune response are transferred to you, you dont actually get the infection convalescence plasma when no other better option is avalible

Question 35

Herd immunity

Answer 35

not actually immunity, that is, not an individual immune response in a population there are susceptible and non susceptible people pathogens have to spread from host to host if there are enough people in a population then the pathogen cannot find or spread to a new host// susceptible person

Question 36

live attenuated vaccinces

Answer 36

a pathogen is weakened by a spontaneous process or by human intervention live attenuated duck egg, serial passages to attapt to a non-human host to reduce virulence cons, are recombination with wild types and attenuated vaccine can become virulent again this pathogen is injected into people in connot cause the disease but can replicate in the host usually provides strong cell and humoral immunity often for life

Question 37

inactivated vaccines

Answer 37

the pathogen is killed or made incapable of reproduction before being used in avaccine phenols and propanol-lactones to inactivate viruses not as strong an immune reaction and usually only humoral immunity is activated

Question 38

subunit vaccines

Answer 38

contain only a single protein or several proteins from the pathogen not as strong an immune reaction adn usually only humoral ex= flu vaccines used today, H and N proteins only

Question 39

toxoid vaccines

Answer 39

tetnus and diptheria vaccines some bacterial infections are due solely to the production of a toxin toxins are produced and inactivated and used in the vaccine via heat denaturation or gluteraldehyde

Question 40

conjugate vaccines

Answer 40

polysaccharides are not immunogenic but are virulence factors (ie capsules) bacterial polysaccharides are chemically bound// conjugated to protiens and used in a vaccinne protein causes the production of Ab against the polysaccharide

Question 41

DNA vaccines

Answer 41

the gene for an antigenic protien from the pathogen is inserted into a DNA plasmid moleucle this plasmid is transfected into host cells plasmid directs the transcription and translation of the pathogen protein presentation of non-self protein on MHC I leads to immune system inactivaiton

Question 42

mRNA vaccines

Answer 42

the gene for an antigenic protein from the pathogen is inserted into a DNA plasmid molecule this plasmid is transfected into E. coli cells which are grown and lysed to obtain a lot of plasmid DNA the plasmid DNA is used with enzymes 9RNA pol) to produce mRNA for the pathogen protein

Question 43

how do we get the mRNA vaccine into you

Answer 43

the mRNA is packaged into lipid nanoparticles these nanoparticles are injected into a person and the mRNA enters into the cytoplasm of the cell cell translates the mRNA into protein which is presented as non=self protein on MHC I and leads to immune system inactivation