2.2 Principles of adaptive immunity to infection

Question 1

Differentiate in bone marrow

Answer 1

Lymphocytes:
- T cells
- B cells

Question 2

Differentiate in thymus?

Answer 2

T cells:
CD4 T cells
CD8 T cells

Question 3

Differentiate in secondary-lymphoid tissues ?

Answer 3

CD4 T cells:
- helper T cells
- regulatory T cells

CD8 T cells:
- Killer T cells

B cells:
- antibodies

Question 4

How do B cells detect antigen?

Answer 4

B cell receptor detects whole antigen (protein) on the surface of pathogens in the ECF

Question 5

How T cells detect antigen?

Answer 5

detects digested antigen fragments (peptides) ‘displayed’ on the surface of other cells in association with MHC molecules

Question 6

B cells secrete ?

Answer 6

Antibodies

Question 7

T cells secrete?

Answer 7

Cytokines

Question 8

T Cell mediated immunity: antigen is brought to lymphoid tissues by?

Answer 8

Dendritic cell -here it is processed and presented

Question 9

Dendritic cells originate from ?

Answer 9

Monocytes
- express PRR

Question 10

How do T cells enter lymphoid tissues?

Answer 10

Via HEVs ( High epithelial valves)
- once here they examine dendritic cells present in paracortex

Question 11

T cells expess:

Answer 11

TCRs that recognize foreign peptides displayed by carrier molecules known as Major Histocompatibility Complex (MHC)

Question 12

Immunological synapse:

Answer 12

Gets info about innate immune system to adaptive immune system about what pathogen is present

Question 13

MHC Class I molecules present peptide fragments of antigen from the

Answer 13

Cytoplasm
Ex: ICF/ cytoplasmic antigens

Question 14

MHC Class II molecules present peptide fragments of
antigen from the

Answer 14

Tissue fluid
Ex ECF antigen

Question 15

CD8+ T cells are only allowed to interact with

Answer 15

MHC Class I : peptides
– Detect intracellular infection

Question 16

CD4+ T cells are only allowed to interact with

Answer 16

MHC Class II : peptides
– Detect extracellular infection

Question 17

When naïve T cells are first activated they

Answer 17

proliferate: CLONAL EXPANSION

Question 18

CD8+ T cells differentiate into

Answer 18

Killer T cells
– aka cytotoxic T lymphocytes (CTL) (marines)

Question 19

CD4+ T cells have a choice for differentiation:

Answer 19

– HELPER T cells (infantry)
– REGULATORY T cells (military police)

Question 20

Naive T cells:

Answer 20

• in ‘SURVEILLANCE MODE’
• They move around the body in search of antigen which is trapped in the secondary lymphoid organs

Question 21

TH1 help

Answer 21

Macrophages

Question 22

TH2 help

Answer 22

B cells make antibody

Question 23

CD4+ T lymphocytes jobs (2):

Answer 23

• Some T helper cells make cytokines to activate macrophages
• Other T helper cells make cytokines to activate B cells

Question 24

Important in vesicular infections where pathogens deliberately infect macrophages
– e.g. mycobacteria such as TB
– Interferon gamma is required to ‘hulkify’ your macrophages

Answer 24

CD4 TH1 cells

Question 25

CD4+ TH2 cells are important for production of

Answer 25

Antibodies: - produce cytokines (such as IL-4) to tell the B cells which type of antibody to secrete – IgG vs IgA vs IgE

Question 26

Regulatory T cell produce

Answer 26

immunosuppressive cytokines such as IL-10

Question 27

Plasma cells

Answer 27

antibody secreting factories

Question 28

Where to plasma cells develop and migrate?

Answer 28

- Develop in germinal centers in lymph node secondary follicles - They migrate to medullary cords of LNs where they secrete antibody into efferent lymph> blood ** some migrate to the bone marrow and produce antibody directly into bloodstream

Question 29

Where do plasma cells remain?

Answer 29

In the lymph nodes - they fire antibody out into circulation that act at the site of infection

Question 30

Basic structure of antibody:

Answer 30

- 2 light chains - 2 heavy chains

Question 31

What happens once the antibody finds its target?

Answer 31

- neutralization: antibody prevents adherence - opsonization: antibody promotes phagocytosis - complement activation: antibody activates complement, which lyses bacteria

Question 32

Answer 32

IgG

Question 33

Answer 33

IgD

Question 34

Answer 34

IgE

Question 35

Answer 35

IgA

Question 36

Answer 36

IgM

Question 37

Which immunoglobulins are be cell receptors?

Answer 37

- IgD - IgM

Question 38

Which immunoglobulins are associated with antibody?

Answer 38

- IgM - IgG - IgA - IgE

Question 39

What is the first antibody produced in the immune system?

Answer 39

IgM

Question 40

IgM:

Answer 40

- Pentamer – binds 10 antigens at once - Agglutinin - Good at triggering the complement cascade

Question 41

When is IgG produced?

Answer 41

Produced after receiving TH2-cell help – CLASS-SWITCHING

Question 42

IgG:

Answer 42

- Neutralising antibody in viral infection - Enhances phagocytosis of bacteria - Triggers complement activation

Question 43

Where is IgA produced?

Answer 43

Produced by B cells in the MALT and secretes onto mucosal surface as a dimer

Question 44

IgA:

Answer 44

- Important neutralising antibody for protection of GIT and respiratory tract - Important component of colostrum and milk for neonatal health

Question 45

Where is IgE produced?

Answer 45

Produced by B cells in response to parasite infections

Question 46

IgE:

Answer 46

- Binds to receptors on the surface of mast cells - Enhances parasite killing response - most specialized

Question 47

Mast cells have receptors for

Answer 47

IgE a recognition triggers degranulation of cells

Question 48

is produced to neutralise viruses and aid in response to bacteria (enhanced phagocytosis and complement activation)

Answer 48

Igg

Question 49

is produced for mucosal defence (neutralising antibody)

Answer 49

IgA

Question 50

is produced for anti-parasite defence to aid mast cell response (assist degranulation)

Answer 50

IgE

Question 51

Lag phase:

Answer 51

Antibody negative during LAG phase (first 5-7 days)

Question 52

Log phase:

Answer 52

IgM > IgG = recent exposure (7-14 days previously)

Question 53

Plateau phase of IgG:

Answer 53

Can last months / years