Chapter 3 Antigen Capture and Presentation to Lymphocytes

Question 1

What can antibodies recognize?

Answer 1

antigens, lipids, nucleic acids, and other types of molecules

Question 2

What happens when naive T cells are activated?

Answer 2

clonal expansion and differentiation into effector T cells

Question 3

What happens when effector T cells are activated?

Answer 3

• activation of macrophages (cell-mediated immunity)
• B cell activation and antibody production (humoral immunity)

Question 4

What activates a naive T cell?

Answer 4

dendritic cell
- though a costimulator B7 and CD28

Question 5

What allows for a naive T cell to get activated?

Answer 5

Costimulator (B7)
CD28

Question 6

What kills a virus infected cell?

Answer 6

CD8+ T cells

Question 7

Where do dendritic cell-associated antigens go?

Answer 7

• lymph nodes
• circulation and spleen

Question 8

What happens to the dendritic cell-associated antigens in the lymph node?

Answer 8

lymph node collects antigens from tissue

Question 9

What happens to the dendritic cell-associated antigens in the spleen?

Answer 9

blood-borne antigens are captured by antigen-presenting cells in the spleen

Question 10

What are the major cytokines produced from dendritic cells?

Answer 10

• TNF
• IL-6
• IL-12
• Type 1 interferons

Question 11

What are the toll-like receptors for dendritic cells?

Answer 11

-TLR 4, 5, 8

Question 12

Why are costimulators important?

Answer 12

Costimulators are important for antigen presentation to by dendritic cells activate naïve T cells

Question 13

What is the major costimulator for naive T cell activation via dendritic cells?

Answer 13

B7

Question 14

Capture and presentation of antigens by _________ cells

Answer 14

dendritic

• also macrophages and B lymphocytes

Question 15

What is a MHC (major histocompatibility complex)?

Answer 15

MHC are expressed on antigen-presenting cells and function to display peptides derived from protein antigens.

Question 16

Does each T Cell recognize every residue of a peptide?

Answer 16

No, the receptor of every T cell recognizes some residues of the peptide and some (polymorphic) residues of the MHC molecule.

Question 17

What are the polymorphic regions of the class I MHC?

Answer 17

a1 and a2

Question 18

What does a3 bind to on the T cell in class I MHC?

Answer 18

CD8 T cell co-receptor

Question 19

CD8+ T cells can only respond to antigen presented by MHC class __ molecules

Answer 19

class I

Question 20

CD4+ T cells can only respond to antigen presented by MHC class __ molecules

Answer 20

class II

Question 21

What are the polymorphic regions of the class II MHC?

Answer 21

a1 and a2

Question 22

a2 and B2 bind to what on the T cell in class II MHC?

Answer 22

CD4 T cell co-receptor

Question 23

Peptide-binding cleft for peptides ______ aa long in Class II MHC

Answer 23

10-30

Question 24

Peptide-binding cleft for peptides ______ aa long in Class I MHC

Answer 24

8-9

Question 25

What genes are the most polymorphic genes in the genome?

Answer 25

Class I and class II MHC genes

Question 26

____________ expression of class I and class II MHC alleles inherited from parents

Answer 26

Codominant

Question 27

Professional antigen presenting cells such as dentrictic cells, macrophages, and B cells activate what type of T cell?

Answer 27

CD4+ helper T cell

Question 28

All nucleated cells can activate what type of T cell?

Answer 28

CD8+ T cell (can kill any virus infected cell)

Question 29

What are the characteristics of MHC molecules?

Answer 29

- broad specificity - displays one peptide at a time - bind only peptides - peptides are aquired druing intracellular assembly - stable surface expression of MHC molecule - very slow off-rate

Question 30

Class II MHC displays peptides from what cellular compartment?

Answer 30

peptide from endocytic vesicle

Question 31

Class I MHC displays peptides from what cellular compartment?

Answer 31

cytosolic peptide transported into ER

Question 32

CD8+ Cytotoxic T cells (CTLs) recognize what kind of antigen presented by MHC class I molecules on an infected cell?

Answer 32

endogenous (cytosolic) antigen

Question 33

What is the class I MHC pathway of processing cytosolic antigens?

Answer 33

- production of proteins in cytosol (some of them are viral proteins) - proteolytic degradation of proteins - transport of peptides from cytosol to ER - assembly of peptide-class I complexes in ER - surface expression of peptide-class I complexes (could have viral proteins on it that CD8+ cells would recognize)

Question 34

CD4+ Helper T cells recognize what type of antigen presented by MHC class II molecules on a professional antigen presenting cell

Answer 34

exogenous antigen

Question 35

What is the class II MHC pathway of processing internalized vesicular antigens?

Answer 35

- uptake of extracellular proteins - processing of internalized proteins in endosomal/lysosomal vesicles - biosynthesis and transport of class II MHC molecules to endosomes - association of processed peptides to class II MHC molecules in vesicles - expression of peptide-MHC complexes on cell surface (some could have pathogen proteins and would be recognized by CD4+ helper T cell)

Question 36

What do dentritic cells use that allows presentation of microbial antigens from infected cells?

Answer 36

Class I MHC-restricted cross-presentation

Question 37

What happens when macrophages are activated?

Answer 37

killing of phagocytosed microbe

Question 38

What happens when B cell antibody secretion occurs?

Answer 38

antibodies bind to antigens

Question 39

What are the 2 ways CD4+ helper T cells use the Class II MHC pathway?

Answer 39

activates macrophages activates B cell antibody secretion