Imunto

Question 1

Regulation of lymphocyte responses prevents:

Answer 1

Responses against self (tolerance),
Tissue damage
Excessive lymphocyte activation during immune responses

Question 2

Immune regulation is

Answer 2

control of the immune response to prevent inappropriate reactions

Question 3

IR us required to

Answer 3

Avoid excessive lymphocyte activation and tissue damage during normal protective responses against infections;
Prevent inappropriate reactions against self antigens (“tolerance”).

Question 4

autoimmunity

Answer 4

immune response against self (auto-) antigen = pathologic

Systemic or organ-specific

Question 5

auto-immune diseases featires

Answer 5

Chronic diseases with prominent inflammation, often caused by failure of tolerance or regulation

Question 6

Fundamental problem

Answer 6

imbalance between immune activation and control;

Question 7

Failure of control mechanisms

Answer 7

is the underlying cause autoimmune diseases;

Question 8

autoimmunity results from

Answer 8

May result from immune responses against self antigens (autoimmunity) or microbial antigens (Crohn’s disease);

Question 9

causes

Answer 9

May be caused by T cells and antibodies;

Question 10

chronic

Answer 10

because it is attacking self-antigen there is always more antigen to attack.

Question 11

Allergy

chronic

Answer 11

Harmful immune responses to non-infectious antigens that cause tissue damage and disease

Question 12

mediated by

1/2

Answer 12

Antibody (IgE) and mast cells – acute anaphylactic shock

Question 13

2/2

Answer 13

Or T cells – delayed type hypersensitivity

Question 14

Hypercytokinemia and Sepsis

causes

Answer 14

Too much immune response
Often in a positive feedback loop
Triggered by pathogens entering the wrong compartment (sepsis) or failure to regulate response to correct level

Question 15

3 phases of Cell mediated immunity

Answer 15

Induction
Effector 
Memory 
 1. Cell infected
DC collects material 
2. MHC:peptide 
TCR interaction 
3. Naïve T becomes effector
4. Effector cell  sees MHC:Peptide on infected cell
Performs function
5. Effector pool contracts to memory

Question 16

Principal mechanism:

Answer 16

immune response eliminates antigen that initiated the response

=> First signal for lymphocyte activation is eliminated

Question 17

Licensing a response – the 3 signal model

Answer 17

Antigen Recognition
Co-stimulation- protien protien interactiom on cell surface
Cytokine Release

all 3 cause t or b cell activation

Question 18

Antigen

Answer 18

Responses against pathogens decline as the infection is eliminated
Apoptosis of lymphocytes that lose their survival signals (antigen, etc)
Memory cells are the survivors

Question 19

Three possible outcomes of infections

Answer 19

Resolution: no tissue damage, returns to normal. Phagocytosis of debris by macrophages.

Repair: healing with scar tissue and regeneration. Fibroblasts and collagen synthesis.

Chronic inflammation: active inflammation and attempts to repair damage ongoing.

Question 20

Tolerance

Answer 20

specific unresponsiveness to an antigen that is induced by exposure of lymphocytes to that antigen (tolerogen vs immunogen)

Question 21

Significance

Answer 21

All individuals are tolerant of their own antigens (self-tolerance); breakdown of self-tolerance results in autoimmunity


Question 22

restoring tolerance may be exploited to prevent

Answer 22

treat autoimmune and allergic diseases

Question 23

Types of tolerance

Answer 23

Tolerance occurs at two time points:

Before the T or B cells ever enter the circulation (central)

Or once in the circulation (peripheral)

Question 24

Central tolerance

Answer 24

destroy self-reactive T or B cells before they enter the circulation

Question 25

why before

Answer 25

Lymphocytes that recognise self antigens are eliminated (deletion) or made harmless in the generative organs as part of the maturation process.

Question 26

AIRE

Answer 26

AutoImmune REgulator

Question 27

not all eptide made in thymus

Answer 27

yes

Question 28

How can a T cell developing in the thymus encounter MHC bearing peptides expressed in other parts of the body?

Answer 28

A specialised transcription factor allows thymic expression of genes that are expressed in peripheral tissues AIRE promotes self tolerance by allowing the thymic expression of genes from other tissues

Question 29

mutations in aire results in

Answer 29

multi-organ autoimmunity

Question 30

Peripheral tolerance

Answer 30

destroy or control any self reactive T or B cells which do enter the circulation

Question 31

3 pathway if b

Answer 31

Antibody Production Memory Affinity Maturation- self reactive b cell can be activated, recognise antigen change shape if antibody to bind on antigen

Question 32

somatic hypermutation

Answer 32

, B cells can change specificity after leaving the bone marrow

Question 33

good

Answer 33

as it improves antibody quality

Question 34

Exposure to environmental antigens or self antigens

Answer 34

can make them less tolerance

Question 35

how many Mechanisms of Peripheral tolerance

Answer 35

``` Normal T cell response Anergy Ignorance Deletion/ AICD Regulation ```

Question 36

Naive T cells needs in order to become activated

Answer 36

need co-stimulatory signals

Question 37

problem

Answer 37

Most cells lack co-stimulatory proteins and MHC class II

Question 38

what happens if n t cell see without co stimulatory protuen

Answer 38

If a naive T cell sees its MHC/peptide ligand without appropriate co stimulatory protein it becomes anergic

Question 39

whats anergic

Answer 39

unresposive, as actiavtion energy is too high

Question 40

what happens if it sees it in the future

Answer 40

less likley to become activated | slower to respond

Question 41

Conditions in anergic

Answer 41

+ Antigen | - Co-stimulation

Question 42

Ignorance Conditions

Answer 42

- Antigen | - Co-stimulation

Question 43

what happens

Answer 43

Antigen may be present in too low a concentration to reach the threshold for T cell receptor triggering not activating so can become anergic

Question 44

happens where

Answer 44

Immunologically privileged sites e.g. eye, (brain) where t cells don't see the antigen Compartmentalisation of cells and antigen controls interactions if they never meet they can't become active

Question 45

Antigen Induced Cell Death (AICD) Conditions

Answer 45

+ Antigen | + FasL

Question 46

how does it work

Answer 46

Activation through the T-cell receptor can result in apoptosis

Question 47

Treg (T regulatory cells) function

Answer 47

inhibit other T cells and other cells by cytokines

Question 48

what do they do

Answer 48

inhibit t cell activation inhibit t cell effector function Secretion of immune-suppressive cytokines inactivation of dendritic cells or responding lymphocytes

Question 49

Treg express transcription factor

Answer 49

FoxP3

Question 50

Mutation in FoxP3 leads to

Answer 50

severe and fatal autoimmune disorder - Immune dysregulation, Polyendocrinopathy, Enteropathy X-linked (IPEX) syndrome.

Question 51

Treg main iL is what

Answer 51

IL-10 (master regulator) cytokine

Question 52

features and functions

Answer 52

``` Key anti-inflammatory cytokine Multi-functional (pleiotropic) Acts on a range of cells Blocks pro-inflammatory cytokine synthesis including TNF, IL-6, IL-8, IFNγ Downregulates Macrophage functions Viral mimics ```

Question 53

“Natural” regulatory T cells (nTreg) develop where

Answer 53

in thymus

Question 54

function

Answer 54

Development (in thymus) requires recognition of self antigen during T cell maturation prevent harmful reactions against self

Question 55

Inducible regulatory T cells (iTreg) | develop from

Answer 55

Develop from mature CD4 T cells

Question 56

function

Answer 56

Develop from mature CD4 T cells that are exposed to antigen in the periphery; no role for thymus May be generated in all immune responses, to limit collateral damage

Question 57

Cytokines prgms

Answer 57

immune response

Question 58

function

Answer 58

They can be inflammatory (increase the response) | Or anti-inflammatory (decrease the response)

Question 59

Chemokines function

Answer 59

Chemokines drive movement around the body

Question 60

Chemokine receptor profiles

Answer 60

change with activation state of the cells

Question 61

how do cell follow

Answer 61

moves up chemokine gradient

Question 62

T helper type defined by

Answer 62

transcription factors

Question 63

Different antibody classes have different

Answer 63

constant regions.

Question 64

T cells shape the antibody response

Answer 64

T cells cytokine drive Ig class switch