Lecture 8: Activation Of Adaptive Immunity Flashcards Preview

COM: Immunology (Midterm) > Lecture 8: Activation Of Adaptive Immunity > Flashcards

Flashcards in Lecture 8: Activation Of Adaptive Immunity Deck (57):
1

Wha cell type presents Ag to naive T cells?

DCs

2

What cell type presents Ag to activated effector T cells?

Macrophages and B cells

3

What HLA regions are found in MHC class II?

DP, DQ, DR

4

What HLA regions are found in MHC class I?

A, B, C

5

HLA genes are highly ___________ and have ____________ expression

Polymorphic; Co-dominant

6

The total _____ genes encoding HLA are in each individual: _____ HLA genes class I (A, B, C) X 2 (mother and father) = _____ genes

6; 3; 6

7

What does it mean that HLA genes are polymorphic and why is this important?

It means that many different alleles are present in population.

This ensures that different individuals are able to present and respond to different microbial peptides

8

What does it mean that HLA genes have co-dominant expression and what is the significance of this?

It means both parental alleles of each MHC genes are expressed

It increases number of different MHC molecules that can present peptides to T cells

9

Do T cells express MHC class II?

No! Only professional APCs express class II MHC

10

Class I MHC molecules have a small __________ for protein fragments

Groove

11

Peptides that are presented within class I MHC are ______ - _____ AAs long

8-11

12

Humans have 3 genes encoding class I MHC: HLA-___, HLA-_____, HLA-_____

HLA-A
HLA-B
HLA-C

13

Class I HLA binds another protein called what?

Beta2-microglobulin

14

Class I MHC presents endogenously processed peptides only for CD___ T cells

CD8+

15

Peptide Ags noncovalently interact with both class I MHC via the ______ and _____ domains

Alpha 1 and alpha 2

16

_______ stabilizes interaction of TCR with class I MHC molecule

CD8+

17

What does CD in CD4 and CD8 stand for?

Cluster of differentiation

18

What does HLA stand for?

Human leukocyte Ag

19

Class I MHC display on the surface protein fragments manufactured by the cells. From immunologic standpoint there are ________ proteins. They are encoded by ________ and ________ pathogens which infected the cell

Endogenous; viruses; intracellular

20

What is the process of peptide loading onto MHC class I?

Intracellular Ag is processed in proteosome, the peptides generated are carried into the ER using TAP1 and TAP2 and are then loaded onto MHC class I and sent to the cell surface

21

Class II MHC are highly ____________ - many different versions exist!

Polymorphic

22

Peptides that bind class II MHC are longer, about _____-____ AAs long

13-25

23

What is the process of class II MHC loading?

1) Extracellular Ags are taken up by professional APCs through phagocytosis, receptor-mediated endocytosis or pinocytosis
2) Peptide s produced in phagolysosome
3) Peptide binding by MHC class II and presented on cell surface


**No empty MHC molecules are displayed on the surface of APCs**

24

When class II MHC is synthesized in ER, it binds the 3rd protein called the _____________ chain

Invariant chain

**Never expressed on the cell surface**

25

What is the significance of the class II MHC molecule binding the invariant chain?

ITT sits in the groove of the MHC class II and prevents MHC class II to bind the cell's own proteins in ER but instead only those from outside

26

Invariant chain, a part called _______ is removed by another protein termed HLA-____ and MHC is loaded with Ags in endosomes

CLIP; HLA-DM

27

MHC receptors have a broad specificity. What is the significance of this?

Many different peptides can bind to the same MHC molecule

28

MHC receptors have a very slow off-rate. What is the significance of this?

MHC molecule displays bound peptide for long enough to be located by T cell

29

What is cross-presentation?

Ags taken up from outside can be presented by class I MHC

30

Ags recognized by B cells can be in soluble or cell surface associated form. Activated B cell is transformed into a _________ cell that secretes Abs. There are primarily found where?

Plasma cell -> primarily found in lymphoid organs

31

Ig___ and Ig___ are associated with BCR

Igalpha and Igbeta

32

Surface Ig can be of what 2 classes?

IgM and IgD

33

Ig___ is the major Ag receptor isotype coexpressed with IgM on the surface of most peripheral B cells in humans

IgD

34

How are the alpha and beta chains of the TCR complex linked?

Disulphide linked

35

What are the 3 invarient domains associated with the TCR complex?

Epsilon/delta(CD3), Gamma/epsilon (CD3), zeta/zeta

36

CD___ is an identification marker for all T cells

CD3

37

_________ APC that expresses class II MHC but not co-stimulatory molecules cannot activate T cells

Resting

38

__________ APC expresses high level of MHC and co-stimulatory molecules

Activated

39

Gamma/delta T cells are a major T cell population in ____________ tissues

Epithelial

40

What type of T cells are directly activated by PRRs (without APCs)?

Gamma/delta T cells

41

What type of T cell is believed to have a prominent role in recognition of lipid Ags?

Gamma/delta T cells

42

Do gamma/delta T cells have memory?

No!

43

Natural killer cells assess whether other cells are abnormal by detecting types and levels of surface-associated
A) MHC class I molecules
B) Nonself molecules
C) Pathogen-associated molecular patterns
D) Pattern recognition receptors
E) Somatically generated cell surface receptors

A) MHC class I molecules

44

What is the most abundant Ig isotype in the blood?

IgG

45

What is a proteolytic fragment of an Ab molecule that contains one intact Ag-binding site called?

Fab

46

T/F: The principal form of cell-mediated immunity that protects against viral infections is mediated by CD8+ CTLs

True

47

T/F: cell-mediated immunity can be adoptively transferred by injecting serum from one individual to another

False

48

The induction phase of a cell-mediated immune response includes which of the following events?
A) CD4+ T cell secretion of IFN-gamma leading to macrophage activation
B) CD8+ T cell lysis of a virally infected cell
C) Clonal expansion of CD8+ T cells with a LN
D) Migration of CD4+ effector T cells from blood vessels into a tissue site of infection
E) Migration of a naive CD4+ T cell from the thymic medulla into the circulation

C) Clonal expansion of CD8+ T cells with a LN

49

Which of the following is a function of TNF that is important in the defense against infections and is likely to be impaired in the setting of TNF blockade?
A) Induction of fever
B) Reduction in cardiac output
C) Enhanced procoagulant activity of endothelial cells
D) Enhanced glucose utilization by muscle cells
E) Induction of E-selectin expression on endothelial cells

E) Induction of E-selectin expression on endothelial cells

50

What is the proteolytic fragment of an Ab molecule that contains the heavy chain constant region called?

Fc

51

Differentiation of Th2 cells from naive precursor cells is dependent on which of the following?
A) TLR ligands
B) Presence of IL-12
C) Absence of IL-12
D) NF-kB
E) Interferon-alpha

C) Absence of IL-12

52

Which of the following mechanisms does not contribute to the generation of a CTL response to a viral infection?
A) DCs phagocytose infected cells or viral particles and present them to naive CD8+ T cells via the class I MHC pathway
B) DCs are infected with the virus and present viral peptides to naive CD8+ T cells via the class I MHC pathway
C) CTLs are directly activated by CD40L expressed on activate Th cells through CD40
D) Th cells secrete IL-2 that promotes proliferation and differentiation of CD8+ T cells
E) Th cells activate APCs via the CD40L-CD40 pathway, and the activated APCs present viral peptides to naive CD8+ T cells via the class I MHC pathway

C) CTLs are directly activated by CD40L expressed on activated Th cells through CD40

53

Which of the following anatomic regions is normally protected from pathogens only by humoral immune responses and not by cell-mediated immune responses?
A) skin
B) intestinal lumen
C) intestinal epithelium
D) CNS
E) spleen

B) intestinal lumen

54

Up to half of the IgG found in the serum of a normal individual is produced by what cells?

Long-lived plasma cells in the bone marrow

55

Treatment of Abs with the enzymes papain under conditions of limited proteolysis results in hinge-region cleavage, yielding monovalent Ag-binding Fab fragments that lack a constant region. Which effector function of Abs would Fab fragments be able to perform?
A) Complement pathway activation
B) ADCC
C) Opsonization
D) Ag cross-linking and precipitation
E) Microbe neutralization

E) Microbe neutralization

56

Activation of the Th1 response requires which of the following?
A) Cross-linking of B cell receptors
B) Binding of CD8 to MHC class I
C) Presence of IL-12 secreted by macrophages
D) IL-2 and IFN-gamma
E) Class switching of IgM to IgE

C) Presence of IL-12 secreted by macrophages

57

IgE is important in defense against parasites because
A) It crosslinks mast cell FcepsilonRI, causing degranulation of inflammatory granules
B) It causes neutrophil chemotaxis
C) It increases production of IL-1 and IFN-gamma
D) It is an indicator of memory B cell function
E) It binds to surface Ags on parasites and causes opsonization

A) It crosslinks mast cell FcepsilonRI, causing degranulation of inflammatory granules