NATURE OF ANTIGENS AND MAJOR HISTOCOMPATIBILITY COMPLEX

Question 1

It is a substance that is specifically recognized by the adaptive immune system

Answer 1

ANTIGEN

Question 2

All antigens are immunogens, but not all immunogens are antigens
T or F

Answer 2

F
All immunogens are antigens, but not all ANTIGENS are Immunogen

Question 3

Factors influencing the Immune Response

Answer 3

Age
Dose
Route of Inoculation
Health status of the host
Genetics

Question 4

It is the ability of an immunogen to stimulate a host response

Answer 4

IMMUNOGENICITY

Question 5

What are the traits of immunogen

Answer 5

Macromolecular size
Chemical composition and molecular complexity
Foreignness
Ability to be processed and presented with MHC molecules

Question 6

It is a precise molecular shapes or configuration recognized by B cells, it binds to an antibody or T cell receptor

Answer 6

EPITOPE

Question 7

A low molecular weight molecule that is too small to stimulate an immune response but when combined with other molecule can induce response

Answer 7

HAPTENS

Question 8

2 types of Epitopes

Answer 8

Linear Epitopes- consist of sequential amino acids on a single polypeptide chain
Conformational Epitopes- result from the folding of one or more polypeptide chains

Question 9

It is a substance administered with an immunogen that increases/enhance the immune response

Answer 9

ADJUVANTS

Question 10

Antigens that belongs to the host

Answer 10

AUTOANTIGEN

Question 11

Antigen that are from other members of the host species that is capable of eliciting an immune response

Answer 11

ALLOANTIGEN

Question 12

Antigen that is from other species such as other animals, plants or microorganisms

Answer 12

HETEROANTIGENS

Question 13

Antigens that exist in unrelated plants or animals but are identical or closely related in structure

Answer 13

HETEROPHILE ANTIGENS

Question 14

A large multi-gene locus consisting of several thousand kilobase pair of DNA on a single chromosome

Answer 14

MAJOR HISTOCOMPATABILITY COMPLEX

Question 15

HLA is located in which chromosome?

Answer 15

Chromosome 6

Question 16

A class of MHC in which molecules are coded for at 3 different locations or loci termed A, B, C

Answer 16

Class I molecules

Question 17

Class of MHC that is situated in the D region and there are several different loci known as DR, DQ, DP

Answer 17

Class II genes

Question 18

Class of MHC which code for complement proteins and cytokines such as tumor necrosis factor

Answer 18

Class III genes

Question 19

CLASS I MHC MOLECULES

Answer 19

Cellular Distribution: All Nucleated Cell
Structure: Alpha Chain & Beta2-microglobulin
Classes: A,B,C
Size of Peptides Bound: 8 to 11 amino acids
Nature of Peptide binding cleft: CLOSED at both ends
Interaction with T-cells: present ENDOGENOUS Antigen to CD8 =T-cytotoxic cells

Question 20

CLASS II MOLECULES

Answer 20

Cellular Distribution: B cells, Thymocytes, Macrophages, Dendritic cells, Thymic epithelial cells
Structure: Alpha Chain & Beta chain
Classes: DP, DR, DG
Size of Peptides Bound: 13 to 18 amino acids
Nature of Peptide binding cleft: OPEN at both ends
Interaction with T-cells: present EXOGENOUS Antigen to CD4 =T-helper cells

Question 21

A phenomenon in which T cells recognizes transported cells bind with peptides in the plasma membrane

Answer 21

ANTIGEN PRESENTATION

Question 22

Class I MHC-Peptide Presentation Pathway

Answer 22

1. Endogenous antigen within the cytosol is degraded by proteasome
2. Peptides are transported to the ER by TAP (transportes associated with Ag processing)
3. Alpha chain binds to Beta2-microglobulin
4. Alpha chain binds to peptide
5. Peptide-Class I is transported to Golgi complex and unto the cell surface
6. Class I MHC binds to CD8+T cell
7. If CD8 recognizes the antigen, cytokines will be released causing destruction of target cell

Question 23

Class II MHC-Peptide Presentation Pathway

Answer 23

1. Class II MHC binds invariant chain to block binding of endogenous antigen
2. MHC complex goes through Golgi Complex
3. Invariant chain is degraded leaving CLIP fragment
4. Exogenous antigen taken in and degraded and routed to intracellular vesicle
5. CLIP fragment exchanged for antigenic peptide
6. Class II MHC antigenic peptide is transported to the cell surface
7. Class II MHC peptide complex binds to CD4+ T cell
8. Upon recognition, clonal expansion will take place and will secrete cytokines that cause antigen-activated B cell to proliferate and produce plasma cells that will create antibody.