MIMG C185A Comprehensive Immunology Final
Assessment Questions
and Answers | 2026
Revised Update | 100% Correct - UCLA.
Question 1
You work with an inbred (syngeneic) strain of mice called the UCLA mice. Their MHC
locus is organized as shown in class: K, I-Aα, I-Aβ, I-Eα, I-Eβ, D, L, L. How many different
types of MHC I molecules will the UCLA mice express on the surface of their APCs?
A) 4
B) 6
C) 8
D) 12
Answer: C) 8
Rationale: The MHC locus shows 9 genes total: K, I-Aα, I-Aβ, I-Eα, I-Eβ, D, L, L. Since the
mice are inbred, both maternal and paternal MHC I genes are identical (homozygous).
The L gene is duplicated, but because the mice are inbred, the two L genes produce
identical proteins that are not distinct. With the standard H-2 locus organization
containing K, D, and L genes (with L being duplicated), the total expressed MHC I
molecules is 8 .
Question 2
For the UCLA mice described in Question 1, how many different types of MHC II will
they express?
,A) 0
B) 2
C) 4
D) 6
Answer: A) 0
Rationale: The alpha and beta chains available cannot recombine with each other. I-Aα
is only compatible with I-Aβ, and I-Eβ is only compatible with I-Eα. These mice lack I-Eα
entirely, so no functional MHC II complexes can form. While I-Aα and I-Aβ are present,
no I-E molecules can assemble because both chains are required .
Question 3
Westwood mice are genetically manipulated and cannot produce TAP1 and TAP2
proteins in any of their cells. What type of microorganisms will these animals be
susceptible to?
A) Extracellular bacteria only
B) Extracellular parasites only
C) Intracellular pathogens (viruses, intracellular bacteria)
D) Both extracellular and intracellular pathogens
Answer: C) Intracellular pathogens (viruses, intracellular bacteria)
Rationale: TAP1/TAP2 transports peptides from the cytosol into the ER for loading onto
MHC class I molecules. Without TAP, MHC I presentation is defective, making these mice
susceptible to intracellular pathogens that require CD8+ T cell responses. CD4+ T cell
development (MHC II-dependent) is unaffected .
Question 4
Mice lacking TAP1/TAP2 will have defects in which of the following?
,A) CD4+ T cell development
B) CD8+ T cell development
C) Both CD4+ and CD8+ T cell development
D) B cell development
Answer: B) CD8+ T cell development
Rationale: Without MHC I presentation, CD8+ T cells cannot be positively selected in
the thymus. CD4+ T cell development depends on MHC II and is therefore unaffected .
Question 5
The MHC locus in humans is called the:
A) H-2 complex
B) HLA complex
C) RAG complex
D) TCR complex
Answer: B) HLA complex
Rationale: In humans, the major histocompatibility complex is called the Human
Leukocyte Antigen (HLA) complex. In mice, it is called the H-2 complex .
Question 6
Which of the following cells does NOT normally express MHC class I?
A) Red blood cells
B) Hepatocytes
C) Dendritic cells
D) Fibroblasts
Answer: A) Red blood cells
, Rationale: Red blood cells lack a nucleus and therefore cannot synthesize MHC class I
molecules. Nearly all nucleated cells express MHC class I .
Question 7
The invariant chain (Ii, CD74) serves what function in MHC II processing?
A) Binds peptide in the ER
B) Blocks the peptide-binding groove and directs trafficking to the endosome
C) Degrades antigen into peptides
D) Transports peptides into the ER
Answer: B) Blocks the peptide-binding groove and directs trafficking to the
endosome
Rationale: The invariant chain blocks the peptide-binding groove of MHC II in the ER
and directs the complex to the endosome, where it is cleaved (leaving CLIP) and then
exchanged for antigenic peptide .
Question 8
HLA-DM functions to:
A) Transport peptides into the ER
B) Catalyze the exchange of CLIP with antigenic peptide in MHC II
C) Degrade invariant chain
D) Transport MHC II to the cell surface
Answer: B) Catalyze the exchange of CLIP with antigenic peptide in MHC II
Rationale: HLA-DM is a chaperone that facilitates the removal of CLIP and the loading
of antigenic peptides onto MHC class II molecules in the endosome .
Assessment Questions
and Answers | 2026
Revised Update | 100% Correct - UCLA.
Question 1
You work with an inbred (syngeneic) strain of mice called the UCLA mice. Their MHC
locus is organized as shown in class: K, I-Aα, I-Aβ, I-Eα, I-Eβ, D, L, L. How many different
types of MHC I molecules will the UCLA mice express on the surface of their APCs?
A) 4
B) 6
C) 8
D) 12
Answer: C) 8
Rationale: The MHC locus shows 9 genes total: K, I-Aα, I-Aβ, I-Eα, I-Eβ, D, L, L. Since the
mice are inbred, both maternal and paternal MHC I genes are identical (homozygous).
The L gene is duplicated, but because the mice are inbred, the two L genes produce
identical proteins that are not distinct. With the standard H-2 locus organization
containing K, D, and L genes (with L being duplicated), the total expressed MHC I
molecules is 8 .
Question 2
For the UCLA mice described in Question 1, how many different types of MHC II will
they express?
,A) 0
B) 2
C) 4
D) 6
Answer: A) 0
Rationale: The alpha and beta chains available cannot recombine with each other. I-Aα
is only compatible with I-Aβ, and I-Eβ is only compatible with I-Eα. These mice lack I-Eα
entirely, so no functional MHC II complexes can form. While I-Aα and I-Aβ are present,
no I-E molecules can assemble because both chains are required .
Question 3
Westwood mice are genetically manipulated and cannot produce TAP1 and TAP2
proteins in any of their cells. What type of microorganisms will these animals be
susceptible to?
A) Extracellular bacteria only
B) Extracellular parasites only
C) Intracellular pathogens (viruses, intracellular bacteria)
D) Both extracellular and intracellular pathogens
Answer: C) Intracellular pathogens (viruses, intracellular bacteria)
Rationale: TAP1/TAP2 transports peptides from the cytosol into the ER for loading onto
MHC class I molecules. Without TAP, MHC I presentation is defective, making these mice
susceptible to intracellular pathogens that require CD8+ T cell responses. CD4+ T cell
development (MHC II-dependent) is unaffected .
Question 4
Mice lacking TAP1/TAP2 will have defects in which of the following?
,A) CD4+ T cell development
B) CD8+ T cell development
C) Both CD4+ and CD8+ T cell development
D) B cell development
Answer: B) CD8+ T cell development
Rationale: Without MHC I presentation, CD8+ T cells cannot be positively selected in
the thymus. CD4+ T cell development depends on MHC II and is therefore unaffected .
Question 5
The MHC locus in humans is called the:
A) H-2 complex
B) HLA complex
C) RAG complex
D) TCR complex
Answer: B) HLA complex
Rationale: In humans, the major histocompatibility complex is called the Human
Leukocyte Antigen (HLA) complex. In mice, it is called the H-2 complex .
Question 6
Which of the following cells does NOT normally express MHC class I?
A) Red blood cells
B) Hepatocytes
C) Dendritic cells
D) Fibroblasts
Answer: A) Red blood cells
, Rationale: Red blood cells lack a nucleus and therefore cannot synthesize MHC class I
molecules. Nearly all nucleated cells express MHC class I .
Question 7
The invariant chain (Ii, CD74) serves what function in MHC II processing?
A) Binds peptide in the ER
B) Blocks the peptide-binding groove and directs trafficking to the endosome
C) Degrades antigen into peptides
D) Transports peptides into the ER
Answer: B) Blocks the peptide-binding groove and directs trafficking to the
endosome
Rationale: The invariant chain blocks the peptide-binding groove of MHC II in the ER
and directs the complex to the endosome, where it is cleaved (leaving CLIP) and then
exchanged for antigenic peptide .
Question 8
HLA-DM functions to:
A) Transport peptides into the ER
B) Catalyze the exchange of CLIP with antigenic peptide in MHC II
C) Degrade invariant chain
D) Transport MHC II to the cell surface
Answer: B) Catalyze the exchange of CLIP with antigenic peptide in MHC II
Rationale: HLA-DM is a chaperone that facilitates the removal of CLIP and the loading
of antigenic peptides onto MHC class II molecules in the endosome .
