Innate Response and Th1 and Th2 Flashcards Preview

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Flashcards in Innate Response and Th1 and Th2 Deck (31):
1

Pathogens target various compartments of the body, which require different host defence mechanisms for eradication.
Name the extracellular compartments and an example of a pathogen that targets these.

Blood, lymph, interstitial spaces, epithelial surfaces
E.g. worms

2

Pathogens target various compartments of the body, which require different host defence mechanisms for eradication.
Name the intracellular compartments and an example of a pathogen that targets these.

Cytoplasm + vesicules
E.g. viruses

3

List the physical defence barrier components of the innate immune system (skin etc), and link them with the mechanisms by which they are breached.

Skin - can be breached by burns, insect bites, medically e.g. central lines,

4

List the cellular components of the innate immune system.

Macrophages / monocytes
Neutrophils
Eosinophils
Basophils / mast cells

5

List the different classes of antibody.

IgM (pentamer)
IgG (monomer)
IgA (secretory dimer)
IgE (monomer)
IgD (monomer)

6

CD4+ cells differentiate to either Th1 or Th2 effector cells.

Distinguish between Th1 and Th2 responses and list the cytokines involved in each, stating the cells that secrete them.

Viruses and bacteria cause IL-12 production which in turn causes the cells to favour Th1 differentiation. Th1 cells produce IFN-gamma, which leads to cell-mediated immunity (help for cytotoxic T cells and macrophages).

Parasitic worms, via IgE, cause IL-4 production which in turn causes the cells to favour Th2 differentiation. Th2 cells produce IL-4,5,13 which leads to humoral immunity (help for B cells for antibody production).

7

List the cells of the adaptive immune system (B-cells, different kinds of T-cells etc), and state the roles they play.

B cells - produce antibodies
CD4 cells (helper) - help with activation of CD8 cells and B cells
CD8 cells (cytotoxic) - remove pathogens and infected host cells
T regulatory cells - help distinguish between self and non-self molecules

8

How does the immune system provide long-lasting
protective immunity?

A fraction of the activated T and B cells become memory cells and provide long-lasting immunity to that infection. Stored in bone marrow and lymph nodes for rapid deployment if infection ever re-occurs.

9

What is the difference between lepromatous TB and military TB?

Lep TB – Th1 dominant, limited disease
Miliary TB – Th2 dominant, disseminated disease

10

Leishmaniasis – two manifestations of the disease exist. What is cutaneous leishmaniasis (orient boils)?

Th1 is dominant response. Limited disease.

11

Leishmaniasis - two manifestations of the disease exist. What is visceral leishmaniasis (Kala-azar/Black Fever)?

Th2 is dominant response. Disseminated disease.

12

Leprosy – two manifestations of the disease exist. What is tuberculoid leprosy?

Th1 is the dominant response. The cytokines are IFN-gamma, and it involves activated macrophages. There are low numbers of organisms. It is a limited disease.

13

Leprosy – two manifestations of the disease exist. What is lepromatous leprosy?

Th2 is the dominant response. Cytokines involved are IL-4,5,13. There are high numbers of organisms. There is hyperglobulinemia. It is disseminated disease.

14

What is the defective immune response disease with defective neutrophils called?

Chronic Granulomatous Disease

15

How do the cells and molecules of the immune system work as an integrated defence system to eliminate or control an infectious agent?

The level of the pathogen increases as the infection is established, and the innate immune response attempts to control it. It reaches a threshold level whereby the adaptive immune response is then activated. The adaptive response then reduces the level of pathogen until it is cleared.

16

How do sentinel cells recognise pathogens?

The toll-like receptors (or other pattern recognition receptors) expressed on sentinel cells e.g. macrophages and dendritic cells, recognise structurally conserved molecules derived from microbes and activate immune cell responses.

17

What do TLR1 and 2 recognise?

gram +ve bacterial products and yeast

18

What does TLR3 recognise?

double-stranded RNA

19

What does TLR4 recognise?

LPS (gram -ve bacteria)

20

What does TLR5 recognise?

flagellin

21

What does TLR6 recognise?

complex with TLR2

22

What do TLR7 and 8 recognise?

single-stranded RNA

23

What does TLR9 recognise?

bacterial DNA

24

Th2 responses lead primarily what cytokine?
What does this cause?

IL-4
Leads to IgE which causes allergies e.g. rhinitis, eczema = type I hypersensitivity.

25

What cells are involved in cell-mediated immunity?

Th1 helper T cells and cytotoxic T cells

26

Where do B cells mature?

bone marrow

27

Where do T cells mature?

thymus

28

How does the immune system respond to a cut arm that becomes infected (with a bacteria that the person has not seen before)?

When there has been a serious cut, the wound bleeds to wash out foreign bodies. The damage (and infection) caused by the cut stimulates the resident macrophages and injured tissue to initiate an inflammatory response, producing cytokines such as IL-1,6,8 and TNF-alpha. A clot forms to seal the wound and fluid enters the site.

Inflammation drives the innate immune response, involving macrophages, NK cells, neutrophils and IgM.

Innate immunity initiates adaptive immunity – resident dendritic cells phagocytose the bacterial antigen. Dendritic cells go to the draining lymph nodes, with the antigen on their MHC molecules, and activate naïve T cells. The CD4+ cells then differentiate to either Th1 or Th2 effector cells. Th1 cells lead to cell-mediated immunity. Th2 cells lead to humoral immunity. B cells become plasma cells which produce huge amounts of diverse antibodies.

29

What are dendritic cells?

antigen presenting cells for the initiation of adaptive immune responses

30

Immature dendritic cells in the tissues mature in the lymphatics and lymph nodes when...?

they meet a microbial challenge i.e. danger signals such as LPS detected by TLR4.

31

How do dendritic cells activate naive T cells?

Via the T cell receptors (along with co-stimulatory molecules such as B7 or CD40).