Immunology - Host Defense & Immune Evasion Flashcards Preview

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Flashcards in Immunology - Host Defense & Immune Evasion Deck (45)
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1

What are the three major functions of interferons (IFN)?

1.) Induce resistance to viral replication in all cells
2.) Increase MHC class 1 expression and antigen presentation in all cells.
3.) Activate NK cells to kill virus-infected cells.

2

What are the two ways the innate immune system is able to distinguish self from non-self?

1.) Pattern recognition receptors (PRRs)
2.) Missing/altered self receptors (NK cells).

3

What are the three ways in which the adaptive immune system is able to distinguish self from non-self?

1.) Antigen presentation (MHC)
2.) Antibodies
3.) T cell receptors

4

What are PAMPs and what is their role?

Pathogen-associated molecular patterns are patterns that are found only in bacteria or other microbes. They are detected when they bind to pattern-recognition receptors which are present on host phagocytic cells.

5

Which type(s) of microbe(s) do macrophages express PRR's for?

Bacteria

6

Which type(s) of microbe(s) do neutrophils express PRRs for?

Bacteria and fungi

7

Where are reserves of neutrophils stored?

Bone marrow

8

In which circumstances do eosinophils' numbers increase?

Parasite infection and in patients with type 1 hypersensitivities. They are a an important defense against helminths.

9

What causes the increase in NK cells during a viral infection?

interferron

10

What is the mechanism used by natural killer cells in causing cell death?

NK cells release perforins and granzymes which perforate membranes and trigger caspase-mediated cell death.

11

Describe the two receptor-binding interactions required for discrimination of self vs. non-self by NK cells.

One receptor is to activate the NK cell to kill, the other is to block the NK cell from killing (MHC 1 receptor). Virus-infected cells express fewer MHC 1 receptors on their surface.

12

What activates the classical pathway?

C1 binding to the C-reactive protein on the pathogen surface.

13

What activates the lectin pathway?

Mannan binding lectin (MBL) and MBL-associated serine protease-2 (MASP-2)

14

What activates the alternative pathway?

Contact of microbial cell wall with C3b

15

What component(s) of the complement system causes opsonization?

C3b

16

What component(s) of the complement system causes the activation of the inflammatory response?

C3a & C5a

17

What is the "formula" for C3 convertase produced by the alternative pathway?

C3bBb

18

What is the "formula" for C3 convertase produced by the classical and lectin pathway(s)?

C4bC2b

19

What is the "formula" for C5 convertase from classical/lectin & alternative pathways?

Classical/lectin pathways: C4bC2bC3b

Alternative pathway: C3bBbC3b

20

Define humoral immunity.

A type of immunity mediated by antibodies secreted by antigen-activated B cells and their progeny plasma cells.

21

What are the features of secondary humoral immune response as compared with primary?

Shorter lag phase
Greater magnitude
Class-switched to IgG (was IgM in primary)

22

Define paratopes

The part of an antibody that recognized an antigen. The antigen-binding site of an antibody.

23

Define epitope

The part of an antigen that is recognized by an antibody.

24

What are surface immunoglobulins and which type(s) of cells have them?

Antibodies expressed on the surface of certain cells.

B-cells and T-cells have surface immunoglobulins

25

Which types of cells recognize native antigen proteins without processing? With processing?

B-cell receptors & antibodies recognize native antigen proteins without processing

T-cell receptors recognize only processed antigens when presented on MHC.

26

Define cell mediated immunity.

Immunity mediated by antigen-activated T cells and the cytokines they secrete.

27

MHC-class 1:

Which cells have it?
What is its function?
What's the result?

All nucleated cells have it
It presents antigens to cytotoxic T (CD8+) cells
It results in T cell-mediated toxicity

28

MHC- class 2:

Which cells have it?
What is its function?
What's the result?

B cells, macrophages and dendritic cells (antigen-presenting cells)
Present antigen to T (CD4+) helper cells
T cell-mediated help (either cell-mediated or antibody mediated response)

29

Which class MHC receptor is used in protection against intracellular pathogens?

MHC class 1 AND MHC class 2

30

Which MHC receptor is used in protection against exogenous antigens?

MHC class 2