Antigens and Antigen Presentation

Question 1

What is an antigen?

Answer 1

Substance that reacts with the products of a specific immune response (molecule recognized by T or B cells)

Question 2

What is an immunogen?

Answer 2

Substance that induces a specific immune response

Question 3

What is an antibody?

Answer 3

A specific protein produced in response to an immunogen and reacts with an antigen

Question 4

What is an epitope?

Answer 4

Site of an Ag that is bound by lymphocyte receptors or antibody

Also known as antigenic determinant

Question 5

What is a Bc epitope?

Answer 5

Specific portion of a macromolecular Ag to which an Ab binds

Question 6

What is a Tc epitope?

Answer 6

The peptide portion that is recognized by a TCR when it is displayed bound to an MHC molecule

Question 7

Can directly stimulate B cells to produce Ab without T cell help

Answer 7

T-Independent Antigen

Question 8

Cannot directly stimulate Ab production without the help of T cells

Answer 8

T-Dependent Antigen

Question 9

How do follicular dendritic cells present antigens?

Answer 9

Display Ags to B-CELLS to initiate humoral immunity

Question 10

What is the role of dendritic cells in antigen capture and display?

Answer 10

1. DC captures antigen and enters lymphatic vessels
2. Transported to lymph node or spleen
3. Protein antigens displayed for recognition by T-CELLS

Question 11

How do B cell epitopes differ from T cell epitopes?

Answer 11

B-Cell:
Antigen is polypeptide, polysaccharide, or nucleic acid
Linear or conformational
Recognized/bound by BCR
Extracellular or on cell surface

T-Cell:
Antigen is a protein
Linear
Bound by TCR only after being processed/display by MHC
Intra- or extracellular

Question 12

How do T-dependent antigens interact with B-cells?

Answer 12

They are processed by APCs, presented via MHC, and bound by TCR

Question 13

What chromosome contains the HLA genes?

Answer 13

6p21.3

Question 14

What is MHC?

Answer 14

Complex of genes encoding cell surface protein molecules that are required for antigen presentation to T cells

Question 15

Which HLA types are preferred for transplantation?

Answer 15

HLA-DR > HLA-B > HLA-A

Question 16

HLA types encoded by MHC Class II Locus

Answer 16

DR, DQ, DP

Question 17

HLA types encoded by MHC Class I Locus

Answer 17

B, C, A

Question 18

What is encoded in MHC Class III Locus?

Answer 18

Complement proteins

Cytokines

Question 19

Which cells contain MHC I?

Answer 19

All nucleated cells

Question 20

Which cells contain MHC II?

Answer 20

APCs

Question 21

What forms the peptide binding groove in MHC I and II?

Answer 21

I: alpha chain only
II: alpha and B2M chain

Question 22

How many peptides can MHC molecules display at one time?

Answer 22

One peptide per MHC

Question 23

In the MHC I pathway, how are degraded peptide fragments transported to the ER?

Answer 23

Via TAP1 and TAP2