immune recognition of pathogens

Question 1

define antigen

Answer 1

anything that binds to a t cell or b cell receptor

Question 2

define foreign antigens

Answer 2

antigens which are not from the body

Question 3

define self antigens

Answer 3

antigens of our own body

Question 4

define immunogen

Answer 4

anything which triggers an immune response

Question 5

define epitope

Answer 5

the part of the antigen which is recognised and binds to the receptor on an immune cell

Question 6

explain the process of antigen recognition

Answer 6

antigen binds to receptor
signalling cascade
gene transcription
effector molecules made e.g. antibodies and cytokines

Question 7

what is another name for antibody?

Answer 7

immunoglobulin

Question 8

how does the antibody made by an immune cell link to the antibody that detects the antigen?

Answer 8

they’re the same antigen

Question 9

how many structures do cells of the innate immune system recognise?

Answer 9

limited

Question 10

name some of the cells of the innate immune system

Answer 10

NK cells
macrophages/monocytes
neutrophils
dendritic cells

Question 11

name some of the cells of the adaptive immune system

Answer 11

t and b lymphocytes

Question 12

how many structures do cells of the adaptive immune system recognise?

Answer 12

millions

Question 13

what receptors recognise pamps?

Answer 13

prrs

pattern recognition receptors

Question 14

what type of receptors are TLRs?

Answer 14

PRRs

Question 15

how many TLRs are there in humans?

Answer 15

10

Question 16

what does TLR4 recognise?

Answer 16

lipopolysaccharides such as bacterial endotoxins

Question 17

what does TLR5 recognise?

Answer 17

flaggelin

Question 18

where are TLRs found?

Answer 18

on the membrane of the immune cells or in the endosome

Question 19

what shape do TLRs have?

Answer 19

horshoe

some exist as dimers

Question 20

when talking about adaptive immunity, what is meant by “particular specificity is rare”?

Answer 20

you don’t have loads of lymphocytes with the same receptor

Question 21

explain the steps of clonal expansion

Answer 21

1 cell recognises an antigen
receives proliferative signal
each daughter cell has the same specificity

Question 22

what are b cell receptors made of?

Answer 22

membrane bound immunoglobulins

Question 23

when do b cells become activated?

Answer 23

when they recognise an antigen

Question 24

what happens to a B cell after it’s activated?

Answer 24

differentiates into a plasma cell

Question 25

in what form do B cells recognise antigens?

Answer 25

free floating/on their own

Question 26

describe the structure of an antibody

Answer 26

``` two identical heavy chains and two identical light chains variable region at the top constant region at the bottom two antigen binding sites held together by disulfide bonds ```

Question 27

what are the heavy and light chains linked by in an antibody?

Answer 27

disulfide bond

Question 28

what does the variable region of the antibody do?

Answer 28

the point where antigens bind

Question 29

what does the constant region of the antibody do?

Answer 29

determines the function of the antibody

Question 30

what are the different types of antibodies?

Answer 30

``` IgM IgG IgA IgE IgD ```

Question 31

what shape is IgM?

Answer 31

a pentameter

Question 32

what shape is IgA in the blood?

Answer 32

monomer

Question 33

what shape is IgA in the mucosa?

Answer 33

dimer

Question 34

what is the Fc region of the antibody?

Answer 34

the tail/bottom half

Question 35

what is the Fab region of the antibody

Answer 35

the top parts

Question 36

what is the first antibody made by B cells?

Answer 36

IgM

Question 37

what is class switching?

Answer 37

when B cells go from making IgM to IgG or any other immunoglobulin

Question 38

in class switching, what happens to the variable and constant regions of the antibody?

Answer 38

variable regions stay the same | constant regions change

Question 39

what does high levels of IgM indicate?

Answer 39

infection was recent

Question 40

what does high levels of IgG indicate?

Answer 40

infection was long time ago

Question 41

how is BCR diversity generated?

Answer 41

somatic DNA recombination

Question 42

what are the different segments in the heavy chain gene of antibodies?

Answer 42

Variable Diversity Joining

Question 43

explain the process of somatic DNA recombination and how this leads to diversity in BCRs

Answer 43

splicing of the DNA, bringing D+J together more splicing to bring V+D together gene transcribed to mRNA splicing to remove introns translation and assembled with light chains to make BCR

Question 44

what form do antigens have to be in to be recognised by T cells?

Answer 44

linear peptides on an APC

Question 45

what are linear peptides?

Answer 45

short linear strings fo AAs

Question 46

what cells can form APCs

Answer 46

dendritic cells | macrophages

Question 47

how do APCs express antigens?

Answer 47

binding them to MHC molecules and presenting them on the surface

Question 48

describe the structure of TCRs

Answer 48

made up of alpha and beta chains connected by a disulfide bridge have a stalk segment, then a transmembrane region and then a cytoplasmic tail

Question 49

where is the variable region in a TCR?

Answer 49

at the top

Question 50

where is the constant region in a TCR?

Answer 50

at the bottom

Question 51

what does CD stand for?

Answer 51

clusters of differentiation

Question 52

when do t cells first express the TCR?

Answer 52

in the thymus

Question 53

what receptors do T helper cells have?

Answer 53

CD4+

Question 54

what receptors do T killer cells have?

Answer 54

CD8+

Question 55

how is TCR diversity generated?

Answer 55

somatic DNA recombination | same mechanism as the BCR recombination but with the a and b chain not the heavy chian

Question 56

what is the most potent APC?

Answer 56

dendritic cells

Question 57

what does MHC stand for?

Answer 57

major histocompatibility complex

Question 58

why does the mhc molecule need to be matched in transplantation?

Answer 58

to avoid graft infection

Question 59

what is an MHC?

Answer 59

a molecule on the APC which presents the peptide for potentiation recognition by T cells

Question 60

what is the MHC gene in humans?

Answer 60

HLA - human leukocyte antigens

Question 61

what are the two classes of MHC proteins?

Answer 61

MHC classes I and II

Question 62

what makes up the peptide binding cleft in MHC class I proteins?

Answer 62

a1 and a2

Question 63

describe the structure of an MHC class 1 protein

Answer 63

three alpha domains and a beta domain

Question 64

which mhc class presents antigens to cytotoxic t cells?

Answer 64

MHC class I

Question 65

which mhc class presents antigens to t helper cells?

Answer 65

MHC class II

Question 66

describe the structure of an MHC class II molecule?

Answer 66

two alpha domains and two beta domains

Question 67

what is the peptide binding cleft made up of in mhc class II proteins?

Answer 67

alpha 1 and beta 1 microglobulins

Question 68

which chromosome has the genes for MHC on it?

Answer 68

chromosome 6

Question 69

what are the two properties that MHCs have to increase the likelihood of peptide binding?

Answer 69

polygenic | polymorphic

Question 70

what are the three classes of MHC class I proteins?

Answer 70

HLA-A HLA-B HLA-C

Question 71

what are the three classes of MHC class II proteins?

Answer 71

DR DP DQ

Question 72

why is polymorphism described as a barrier to organ transplantation?

Answer 72

different MHC molecules on the graft are recognised as foreign, tissue is rejected and an immune response is triggered

Question 73

what is coeliac disease?

Answer 73

inappropriate immune response to gluten which causes chronic inflammation of small intestine because blunted villi leads to poor absorption of nutrients

Question 74

how is coeliac disease treated?

Answer 74

diet where gluten is excluded

Question 75

what is the cause of coeliac disease?

Answer 75

HLA-DQ2 and HLA-DQ8 bind gliadin peptides in gluten that cause disease when presented to T cells

Question 76

what happens to lymphocytes that have high self-reactivity?

Answer 76

killed