Chapter 3- Antigen Capture and Presentation to Lymphocytes

Question 1

what are the antigen presenting cells and what is each of their response

Answer 1

• dendritic cell: naive T cell activation, clonal expansion and differentiation into effector T cells
• Macrophage: effector T cell activation: activation of macrophages (cell mediated immunity)
• B cell: effector T cell activation: B cell activation and antibody production (humoral immunity)

Question 2

what is the function of cytotoxic T cells and what MHC class do they recognize

Answer 2

killing of infected cells, recognize CD8+ cells

Question 3

what is the role of dendritic cells in antigen capture and presentation in lymph node and blood

Answer 3

• lymph node collects antigen from tissue
• blood borne antigens are captured by antigen presenting cells in the spleen

Question 4

what are costimulators important for

Answer 4

antigen presentation to dendritic cells to activate naive T cells

Question 5

CD8T cells can only respond to antigen presented by _____

Answer 5

MHC Class I molecules

Question 6

CD4T cells can only respond to antigen presented by _____

Answer 6

MHC Class II molecules

Question 7

describe the structure of the Class I MHC molecule- polymorphic regions, peptide length and what binds co-receptor

Answer 7

• polymorphic regions: alpha1 and alpha2
• peptide binding cleft for peptides 8-9 amino acids long
• alpha3 binds CD8T cell co- receptor

Question 8

describe the structure of the class II MHC molecule- polymorphic regions, peptide length and what binds co-receptor

Answer 8

• polymorphic regions: alpha1 and beta1
• peptide binding cleft for peptides 10-30 amino acids long
• alpha2 and beta2 binds CD4 T cell co receptor

Question 9

what genes are the most polymorphic genes in the genome

Answer 9

Class I and II MHC

Question 10

the total number of HLA alleles in the human population is about _____ class I alleles and ____ class II alleles

Answer 10

10,000; 3,000

Question 11

codominant expression of alleles inherited from ___

Answer 11

parents

Question 12

what are polymorphic genes

Answer 12

many different alleles are present in the population

Question 13

what is the significance of polymorphic genes

Answer 13

different individuals are able to present and respond to different microbial peptides

Question 14

what is codominant expression

Answer 14

both parental alleles of each MHC gene are expressed

Question 15

what is the significance of codominant expression

Answer 15

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

Question 16

what are the MHC expressing cell types

Answer 16

-Class II: dendritic cells, macrophages, B cells
- Class I: all nucleated cells

Question 17

what is the significant of the Class II MHC expressing cell types

Answer 17

CD4+ helper T lymphocytes interact with dendritic cells, macrophages, and B lymphocytes

Question 18

what is the significance of the Class I MHC expressing cell types

Answer 18

• CD8+ CTLs can kill any type of virus infected cell

Question 19

what do CD8+ Cytotoxic T cells recognize

Answer 19

endogenous antigen presented by MHC class I molecules on an infected cell

Question 20

what do CD4+ Helper T cells recognize

Answer 20

exogenous antigen presented by MHC Class II molecules on a professional APC

Question 21

what is the Class I MHC pathway of processing cytosolic antigens

Answer 21

-production of proteins in the cytosol
- proteolytic degradation of proteins
- transport of peptides form cytosol to ER
- assembly of peptide class I complexes in ER
- surface expression of peptide class I complexes

Question 22

what is the class II MHC pathway of processing internalized vesicular antigens

Answer 22

-uptake of extracellular proteins into vesicular compartments of APC
- processing of internalized proteins in endosomal/lysosomal vesicles
- association of processed peptides with class II MHC molecules in vesicles
- expression of peptide MHC complexes on cell surface

Question 23

what are O antigens

Answer 23

polysaccharides

Question 24

what can antibodies recognize

Answer 24

lipids, nucleic acids, and other types of molecules