W7- Lecture 31- Specific Immunity

Question 1

What do CD4 helper T cells help activate in the adaptive immune response ?

Answer 1

B cells (to turn into plasma cells ) that produce antibodies

CD8 cytotoxic T cells that lyse infected cells

Question 2

Where are T cells matured ?

+ what selection do they under go

Answer 2

In the thymus

Both positive and negative selection

Question 3

Where are b cells matured ?

Answer 3

Bone marrow

Only positive selection

Question 4

What are the major difference between the production of B & T cells

Answer 4

B cells develop in the bone marrow constantly - mature in bone marrow

T cells the majority of them produced before puberty - mature in thymus

Question 5

With maturity T cells develop distinct membrane bound membrane making two compounds callled

Answer 5

CD4+
CD8
Both T cells

Question 6

Describe how T cells and B cells recognise foreign pathogens differently

Answer 6

Cytotoxic T cells - recognise proteins/ other long chain molecules (broader range of target pathogenic epitopes )
-protein antigens

B cells - recognise epitopes not whole proteins or long chains . More specific
-proteins, lipids carbs and nucleic acids

Question 7

What is an antigen

Answer 7

Non-self molecular configuration

activate the adaptive response eg antibody production

Question 8

What do lymphocytes recognise to produce an immune response?

Answer 8

Epitopes

Question 9

What is Immunogenicity

Answer 9

an ability to induce a response mediated by the production of specific T cells or specific antibodies.

Question 10

What is Reactivity in terms of immune responses

Answer 10

the ability to react with antibodies or specific T cells

Question 11

What is a complete antigen vs partial antigen

Answer 11

Complete - has reactivity and immunogenicity

Partial- reactivity but lack Immunogenicity

Question 12

After coming in contact with an immune cell when does an antigen go ?

Answer 12

Via blood to spleen
Or
Via lymph to lymph node

Where they are trapped by recticular fibres of the reticular cells
Or
in the case of the mucosal membrane, antigens are trapped by mucosa-associated lymphatic tissue (MALT).

Question 13

What are major histocompatibility complex (MHC)

AKA human leukocyte action

Answer 13

Molecules (products of 12 alleles) that are expressed on the surface of cells that are important in immune responses

Guide T cells
Bind epitopes to antigens + present them to T cells
(identical to us )

Question 14

Name the major difference between MGC class 1 & 2

Answer 14

Class 1- presents self proteins

Class 2 - foreign antigens presented

Question 15

Where are are MHC aka HLA’s expressed

Answer 15

Every cell of the body except Red blood cells

Question 16

Where are MHC 1 & 2 found

What do these receptors play n important roles in treatment

Answer 16

1- in plasma membrane of all body cells

2-on membranes of antigen presenting cells
E.g thymidine cells + active T cells

• important role in rejection of Donor tissue

Question 17

What is the difference between where/ how B and T cells recognise antigens

Answer 17

B cells - recognise antigens in body fluids

T cells -only recognise antigens associated with MHC

Question 18

Describe exogenous antigen processing (antigens found in body fluid )

Answer 18

Ingest antigen
Antigen digested into peptide fragments
Peptide fragments transferred to vesicle + MHC 2 molecule line inner membrane of vesicle
Vesicles fuse
Two components bind forming a complex
Vesicle undergo exocytosis
The MHC 2 attached to antigen fragments is presented on cell surface

Question 19

After exogenous antigen processing where does the antigen presenting cell migrate to ?
+ purpose

Answer 19

Lymphatic tissue

to be presented to T cells

Question 20

Describe endogenous antigen processing (antigens produced within cell)

Answer 20

Fragments associate with MHC 1
Forming complex
Complex moves to cell membrane where the antigen is displaced on the surface

Question 21

Name the two steps of T cell activation

Answer 21

Co-stimulation

Helper T cell activation

Question 22

Describe the co-stimulation of T cells

Cause
Name 1

Answer 22

happens when T cell binds with specific antigen on antigen presenting cell
Activation
Causing proliferation and differentiation
Cytokines e.gInterleukin 2

Question 23

Where does the proliferation ans differentiation of T cells occur ?

Answer 23

Secondary lymphatic organs/ tissues

E.g tonsils

Question 24

Describe the T cell activation by helpers T cell

Answer 24

Cd4+ cells normally develop into T helper cells
helper cells recognise MHC2/antigen complex
(if co-stimulated ) secrete cytokines e.h il 2
Triggering T cell proliferation
+ proliferation of B cells and NK cells

Question 25

What do activated t helper cells produce ?

Answer 25

Clones that secrete cytokines
+
Memory cells

Question 26

What are cytokines

Secreted by 3 x e.g

Answer 26

hormones that can stimulate or inhibit cellular differentiation, proliferation and growth

lymphocytes, monocytes, fibroblasts

Question 27

Name a number of cytokines

8*

Answer 27

interleukins (1-5),
tumour necrosis factor,
transforming growth factor beta (TGF- ß), Gamma interferon (gamma -IFN),
alpha and Beta interferons (alpha and ß IFNs)
Lymphotoxin
Perforin
macrophage migration inhibiting factor.

Question 28

Where ate cytotoxic T cells derived from ?

Answer 28

CD8+ cells

Question 29

Describe the activation of cytotoxic T cells

Answer 29

Cytotoxic T cells recognise the antigen/MHC2 complex (on a virus infected/cancerous/transplanted cell )
Co-stimulation which il-2 (released by t helper cells )
Can only take place if the if the helper cells have come into contact with them same complex

Activation = proliferatoon

Question 30

After activation what happens to cytotoxic T cells

Answer 30

Rapidly proliferate
+ destroy target cells by binding &
Secreting porforin
To secretion lymphotoxins (that punch holes in bacteria )

Ct cells also secrete gamma interferon + activates phagocytes at the site of infection

Question 31

What can cytotoxic T cells differentiate inti

Answer 31

Clones of themselves aka multiply via clonal——

Memory cel,s

Question 32

Describe the development of T-lymphocyte in thymus by thymic education.

Selections
Mediated by

Answer 32

Proliferation of progenitor cells

Most cell’s got through apoptosis (90-98%)

Positive selection- those cells that can bind with the MHC receptor are positively selected
Mediated by thymic epithetical cells

Negative selection - those that bind too strongly with MHC and negatively selected (because would kill own cells )
Mediated by bone marrow derived dendritic cells + macrophage

Question 33

Which T cells recognise MHC 1 & 2C

Answer 33

CD8

CD4