CHAPTER 2: Nature of Antigens and the Major Histocompatibility Complex

Question 1

All of the following are characteristics of an effective immunogen except:
a. internal complexity.
b. large molecular weight.
c. the presence of numerous epitopes.
d. found on host cells.

Answer 1

d. found on host cells.

Question 2

Which of the following best describes a hapten?
a. Cannot react with antibody
b. Antigenic only when coupled to a carrier
c. Has multiple determinant sites
d. A large chemically complex molecule

Answer 2

b. Antigenic only when coupled to a carrier

Question 3

Which would be the most effective immunogen?
a. Protein with a molecular weight of 200,000
b. Nylon polymer with a molecular weight of 250,000
c. Polysaccharide with a molecular weight of 220,000
d. Protein with a molecular weight of 175,000

Answer 3

a. Protein with a molecular weight of 200,000

Question 4

Which of the following individuals would likely
respond most strongly to a bacterial infection?
a. An adult who is 75 years of age
b. A malnourished 40-year-old
c. A weightlifter who is 35 years old
d. A newborn baby

Answer 4

c. A weightlifter who is 35 years old

Question 5

Which best describes an epitope?
a. A peptide that must be at least 10,000 MW
b. An area of an immunogen recognized only by T cells
c. A segment of sequential amino acids only
d. A key portion of the immunogen

Answer 5

d. A key portion of the immunogen

Question 6

Adjuvants act by which of the following methods?
a. Protects antigen from being degraded
b. Facilitates rapid escape from the tissues
c. Limits the area of the immune response
d. Decreases number of APCs

Answer 6

a. Protects antigen from being degraded

Question 7

A heterophile antigen is one that
a. is a self-antigen.
b. exists in unrelated plants or animals.
c. has been used previously to stimulate antibody
response.
d. is from the same species but is different from
the host.

Answer 7

b. exists in unrelated plants or animals.

Question 8

Which of the following is true of class II MHC (HLA) antigens?
a. They are found on B cells and macrophages.
b. They are found on all nucleated cells.
c. They all originate at one locus.
d. They are coded for on chromosome 9.

Answer 8

a. They are found on B cells and macrophages.

Question 9

Class II MHC molecules are recognized by which of the following?
a. CD4+ T cells
b. CD8+ T cells
c. Natural killer cells
d. Neutrophils

Answer 9

a. CD4+ T cells

Question 10

Which of the following best describes the role of TAP?
a. They bind to class II molecules to help block the antigen-binding site.
b. They bind to class I proteins in proteasomes.
c. They transport peptides into the lumen of the endoplasmic reticulum.
d. They help cleave peptides for transport to endosomes.

Answer 10

c. They transport peptides into the lumen of the endoplasmic reticulum.

Question 11

What is the purpose of the invariant chain in antigen processing associated with class II MHC molecules?
a. Helps transport peptides to the binding site
b. Blocks binding of endogenous peptides
c. Binds to CD8+ T cells
d. Cleaves peptides into the proper size for binding

Answer 11

b. Blocks binding of endogenous peptides

Question 12

An individual is recovering from a bacterial infection and tests positive for antibodies to a protein normally found in the cytoplasm of this bacterium. Which of the following statements is true of this situation?
a. Class I molecules have presented bacterial antigen to CD8+ T cells.
b. Class I molecules have presented bacterial antigen to CD4+ T cells.
c. Class II molecules have presented bacterial antigen to CD4+ T cells.
d. B cells have recognized bacterial antigen without help from T cells.

Answer 12

c. Class II molecules have presented bacterial antigen to CD4+ T cells.

Question 13

In relation to a human, alloantigens would need to be considered in which of the following events?
a. Transplantation of a kidney from one individual to another
b. Vaccination with the polysaccharide coat of a bacterial cell
c. Oral administration of a live but heat-killed virus particle
d. Grafting skin from one area of the body to another

Answer 13

a. Transplantation of a kidney from one individual to another

Question 14

Which is characteristic of class I MHC molecules?
a. Consists of one α and one β chain
b. Binds peptides made within the cell
c. Able to bind whole proteins
d. Coded for by DR, DP, and DQ genes

Answer 14

b. Binds peptides made within the cell

Question 15

Class I MHC antigens E and G serve which function?
a. Enhance the response by macrophages
b. Transport antigen for recognition by CD4+ T cells
c. Bind to A, B, and C antigens to protect the binding site
d. Protect fetal tissue from destruction by NK cells

Answer 15

d. Protect fetal tissue from destruction by NK cells

Question 16

Which best explains the difference between immunogens and antigens?
a. Only antigens are large enough to be recognized
by T cells.
b. Only immunogens can react with antibody.
c. Only immunogens can trigger an immune response.
d. Only antigens are recognized as foreign.

Answer 16

c. Only immunogens can trigger an immune response.

Question 17

When a child inherits one set of six HLA genes together from one parent, this is called a(n)
a. genotype.
b. haplotype.
c. phenotype.
d. allotype.

Answer 17

b. haplotype.

Question 18

HLA molecules A, B, and C belong to which MHC class?
a. Class I
b. Class II
c. Class III
d. Class IV

Answer 18

a. Class I