Unit 11 Question Bank
The five tabs are the five sections of the real paper. Items tagged
Past Paper 2019 or 2020 are the genuine questions, reproduced verbatim.
Items tagged Slide come from the TMU lecture; items tagged Janeway's are built
from the textbook to cover examinable ground. Nothing is invented. Janeway's 10e is a reflowed
edition with no printed page numbers, so it is cited by numbered section (§1-14), not by page.
0 / 27 answered
1Which cell is the most powerful APC and can elicit primary immune response?
Answer: B
The lecture states it directly: DC is the most powerful APC among the three professional APCs; DC can activate naïve T cells, so DC is the initiator of the immune response. The phrase primary immune response is the key — it means activating a naïve T cell, and only the DC can. Neutrophils are not APCs at all.Past Papers 2019 & 2020, Section III Q8 — verbatim, both years
2Which one is the characteristic of mature DCs?
Answer: C
Maturation is a one-way trade: uptake and processing fall from ++++ to +, while presentation rises from + to ++++. All three distractors accurately describe the immature DC — so the question is testing which way round the trade runs. The reason is geographical: an immature DC sits in tissue collecting antigen, a mature DC migrates to the lymph node to display it.Past Papers 2019 & 2020, Section III Q14 · TMU Lecture 8 — Antigen Presenting Cells Slide 11
3Professional antigen-presenting cells are:
Answer: D
The three professional APCs are exactly the cells that express MHC class II constitutively — the professional list and the class II distribution list from Unit 10 are the same list. The last option names non-professional APCs, which can be induced to express class II but not constitutively.Past Papers 2019 & 2020, Section II · TMU Lecture 8 — Antigen Presenting Cells Slide 5
4Which of the following is a NON-professional antigen-presenting cell?
Answer: A
Non-professional APCs include fibroblasts, thymic and thyroid epithelial cells, glial cells, pancreatic β cells and vascular endothelial cells. They can be induced to express class II under inflammatory conditions but lack constitutive expression and the co-stimulatory molecules needed to activate a naïve T cell.TMU Lecture 8 — Antigen Presenting Cells Slide 5
5In the class I pathway, endogenous antigen is degraded by:
Answer: B
The proteasome — a large cylindrical particle with a central channel that cleaves peptide bonds. Lysosomal degradation in endosomes belongs to the class II pathway, handling exogenous antigen.TMU Lecture 8 — Antigen Presenting Cells Slides 21–22
6How do peptides generated in the cytosol reach MHC class I molecules?
Answer: C
The class I pathway solves a geography problem: class I is assembled inside the ER, but its peptides are out in the cytosol on the wrong side of a membrane. TAP1/TAP2 — themselves MHC-encoded, from Unit 10 — pump the fragments in.TMU Lecture 8 — Antigen Presenting Cells Slide 22 · Unit 10
7Endogenous antigen presented on MHC class I is recognised by:
Answer: D
Endogenous → proteasome → TAP → class I → CD8⁺. The logic: cytosolic antigen means the cell itself is making it, so the cell is infected or transformed and the correct response is to kill it — which is the CTL's job. Remember class I × CD8 = 8.TMU Lecture 8 — Antigen Presenting Cells Slides 18, 22
8Exogenous antigen is presented to which T-cell subset, on which MHC class?
Answer: A
Exogenous → endocytosis → lysosome → class II → CD4⁺. External antigen means the APC itself is healthy — it is a scout reporting, not a compromised cell — so the correct response is to organise help rather than kill the presenter. Class II × CD4 = 8.TMU Lecture 8 — Antigen Presenting Cells Slide 23
9Which cells are able to present antigen on MHC class I?
Answer: B
Class I is on all nucleated cells, because any cell can be infected by a virus and must be able to report its own cytoplasm. Class II — and therefore the class II pathway — is restricted to professional APCs.TMU Lecture 8 — Antigen Presenting Cells Slide 18 · Unit 10 Slide 15
10How does a B cell take up antigen for presentation?
Answer: C
Ig-mediated uptake, rated ++++ — the most efficient of the three professional APCs, because the BCR concentrates the cell's own specific antigen rather than sampling indiscriminately. That is why B cells specialise in soluble antigens, toxins and viruses, which macrophages capture poorly.TMU Lecture 8 — Antigen Presenting Cells Slide 14
11Which APC expresses MHC and co-stimulatory molecules constitutively at the highest level?
Answer: D
The DC alone is constitutively ++++ for both MHC and B7. That is precisely why it can deliver signal 1 and signal 2 to a naïve T cell without needing to be activated first — and therefore why it is the only initiator of a primary response. Macrophage MHC expression is inducible, and both macrophage and B-cell B7 is inducible.TMU Lecture 8 — Antigen Presenting Cells Slide 14
12An immature dendritic cell is characterised by:
Answer: A
The immature DC is the collector: uptake ++++, processing ++++, presentation +, with low co-stimulatory molecules, sitting where pathogens arrive. Everything else listed describes the mature DC after it has migrated to a lymph node.TMU Lecture 8 — Antigen Presenting Cells Slide 11
13Which cytokines does a mature dendritic cell secrete?
Answer: B
IL-12 and IL-18 in particular matter, because IL-12 is the cytokine that drives Th0 → Th1 (Unit 5). So the mature DC does not merely present antigen — it supplies signal 3 and helps decide which kind of effector T cell results.TMU Lecture 8 — Antigen Presenting Cells Slide 11 · Unit 5
14Why can macrophages and B cells not initiate a primary immune response?
Answer: C
Both have MHC class II and both process antigen well — but their co-stimulatory (B7) expression is inducible, not constitutive. A naïve T cell needs both signals simultaneously, and only the DC is permanently equipped to give them. Macrophages and B cells present very effectively to already activated T cells.TMU Lecture 8 — Antigen Presenting Cells Slide 14 · TMU Lecture 7 — Immune Cells Slide 73
15A virus-infected liver cell displays viral peptide to a passing CD8⁺ T cell. Which pathway produced that display?
Answer: D
The liver cell is making viral protein, so the antigen is endogenous and enters the class I route: proteasome → TAP → class I → CD8⁺. A hepatocyte is not a professional APC and has no class II — but it does have class I, like every nucleated cell, and that is exactly the point of class I being universal.TMU Lecture 8 — Antigen Presenting Cells Slides 17–18
16Which statement about antigen recognition is correct?
Answer: A
This is the reason APCs exist. The BCR touches the intact molecule, so B cells read conformational epitopes on native antigen (Unit 2). The TCR can only read a linear peptide sitting in an MHC groove — so something must first capture, cut up and display the antigen.TMU Lecture 8 — Antigen Presenting Cells Slide 3
1 Antigen-presenting cell (APC) — 3 marks+
Cell populations that can capture and process antigens, and present them to T lymphocytes. Professional APCs — dendritic cells, macrophages and B cells — express MHC class II constitutively. Non-professional APCs include fibroblasts, thymic and thyroid epithelial cells, glial cells, pancreatic β cells and vascular endothelial cells.Past Paper 2019, Section I Q4 · TMU Lecture 8 — Antigen Presenting Cells Slides 4–5
2 Dendritic cell (DC) — 3 marks+
The most powerful APC and the only one that can activate naïve T cells — hence the initiator of the immune response. Discovered by Steinman in 1973 (Nobel Prize 2011). Classified by derivation into myeloid DC (DC1) and lymphoid DC (DC2), and by function into immature and mature. DCs express MHC and co-stimulatory molecules constitutively.TMU Lecture 8 — Antigen Presenting Cells Slides 8–11, 14
3 Immature and mature DC — 3 marks+
Immature DC: antigen uptake ++++, processing ++++, presentation +, low co-stimulatory molecules, resident in peripheral tissue. Mature DC: uptake +, processing +, presentation ++++, high MHC and co-stimulatory molecules, secretes IL-12, IL-18, IFN-γ and chemokines, resident in secondary lymphoid organs. Maturation is a one-way trade of collecting for reporting.TMU Lecture 8 — Antigen Presenting Cells Slide 11
4 Endogenous and exogenous antigen — 3 marks+
Endogenous antigen comes from inside the cell — viral proteins, tumour proteins — and is processed by the class I pathway. Exogenous antigen comes from outside the cell — bacteria, cells, protein — is taken up by endocytosis and processed by the class II pathway.TMU Lecture 8 — Antigen Presenting Cells Slide 17
5 Class I presentation pathway — 3 marks+
① Antigen protein is synthesised by the target cell. ② It is cleaved into peptides by proteasomes. ③ Peptides are transported from the cytosol to the rough ER (by TAP). ④ They assemble with class I MHC. ⑤ The peptide–class I complex is expressed on the cell surface and presented to CD8⁺ T cells. Available to all nucleated cells.TMU Lecture 8 — Antigen Presenting Cells Slides 18, 22
6 Class II presentation pathway — 3 marks+
① Exogenous antigen is taken up by endocytosis into an APC. ② It is degraded into peptide fragments in the endosome/lysosome. ③ Peptides combine with class II MHC molecules. ④ The peptide–class II complex is displayed on the surface and presented to CD4⁺ helper T cells. Restricted to professional APCs.TMU Lecture 8 — Antigen Presenting Cells Slide 23
1Professional APCs include ? , ? and ? .3 mark(s)
Exactly the cells that express MHC class II constitutively — the professional-APC list and the class II distribution list are the same list.
Past Papers 2019 & 2020, Section II2Endogenous antigen is degraded by the ? , transported to the ER by ? , loaded onto MHC class ? and presented to ? T cells.4 mark(s)
The pathway solves a geography problem: class I is assembled in the ER but its peptides are in the cytosol, so they must be chopped outside and pumped in.
TMU Lecture 8 — Antigen Presenting Cells Slides 18, 223Exogenous antigen is taken up by ? , degraded in the ? , loaded onto MHC class ? and presented to ? T cells.4 mark(s)
No transporter is needed here — antigen and class II arrive in the same vesicular compartment, so the peptide is simply loaded where they meet.
TMU Lecture 8 — Antigen Presenting Cells Slide 234An immature DC has antigen uptake ? and antigen presentation ? ; a mature DC has uptake ? and presentation ? .4 mark(s)
This reversal is MCQ Q14. The immature DC collects in peripheral tissue; the mature DC reports in the lymph node.
TMU Lecture 8 — Antigen Presenting Cells Slide 115Dendritic cells are classified by derivation into ? DC (DC1) and ? DC (DC2).2 mark(s)
By function they are additionally classified as immature or mature.
TMU Lecture 8 — Antigen Presenting Cells Slide 101Dendritic cells are the only professional APC able to activate naïve T cells.
TRUE
True — which is why the DC is called the initiator of the immune response and why it is the answer to MCQ Q8. It alone expresses MHC and co-stimulatory molecules constitutively, so it can deliver signal 1 and signal 2 together without needing prior activation.TMU Lecture 8 — Antigen Presenting Cells Slides 11, 14
2Mature dendritic cells take up antigen more efficiently than immature ones.
FALSE
False — the reverse. Uptake falls from ++++ to + on maturation, while presentation rises from + to ++++. The DC stops sampling and starts reporting, because it cannot be in the peripheral tissue and the lymph node at the same time.TMU Lecture 8 — Antigen Presenting Cells Slide 11
3Only professional APCs can present antigen on MHC class I.
FALSE
False. All nucleated cells present on class I — any cell can be infected and must be able to report its own cytoplasm. The restriction to professional APCs applies to class II.TMU Lecture 8 — Antigen Presenting Cells Slide 18 · Unit 10
4T cells can recognise native, unprocessed antigen.
FALSE
False. T cells recognise only antigen that has been processed and presented on MHC. B cells are the ones that read native antigen directly through the BCR — and that difference is the entire reason APCs exist.TMU Lecture 8 — Antigen Presenting Cells Slide 3
5B cells present soluble antigens more effectively than macrophages or dendritic cells.
TRUE
True. The BCR captures and concentrates the cell's own specific antigen, giving Ig-mediated uptake rated ++++. Macrophages and DCs cannot capture soluble antigen efficiently — so the B cell fills exactly that gap.TMU Lecture 8 — Antigen Presenting Cells Slide 14 · TMU Lecture 7 — Immune Cells Slide 209
6Vascular endothelial cells are professional antigen-presenting cells.
FALSE
False — they are non-professional APCs, along with fibroblasts, thymic and thyroid epithelium, glial cells and pancreatic β cells. They can be induced to express class II under inflammatory conditions but do not do so constitutively.TMU Lecture 8 — Antigen Presenting Cells Slide 5
1
Compare the class I and class II antigen presentation pathways.
6 marks
| Class I pathway | Class II pathway | |
|---|---|---|
| Antigen source | Endogenous — synthesised within the cell (viral, tumour protein) | Exogenous — taken up from outside (bacteria, cells, protein) |
| Uptake | None — already in the cytosol | Endocytosis |
| Degraded by | Proteasome | Endosome / lysosome |
| Transport | TAP, cytosol → rough ER | Vesicular trafficking |
| Loaded onto | MHC class I | MHC class II |
| Presented to | CD8⁺ T cells | CD4⁺ T cells |
| Performed by | All nucleated cells | Professional APCs only |
| Consequence | Killing of the presenting cell | Recruitment of help / organisation of a response |
The organising idea worth stating: the compartment the antigen occupies determines the MHC class, which determines the T-cell subset, which determines the outcome. Cytosolic antigen means the cell itself is compromised, so it is killed; external antigen means the APC is a healthy scout, so help is recruited instead.
Marking guide: 0.75 per row. The source, MHC class and T-cell rows are essential; stating the compartment-determines-outcome logic secures full marks.
2
Compare immature and mature dendritic cells.
6 marks
| Immature DC | Mature DC | |
|---|---|---|
| MHC I / II | +++ | ++++ |
| Co-stimulatory molecules (B7, ICAM-1, LFA-3) | Low level | High level |
| Antigen uptake | ++++ | + |
| Antigen processing | ++++ | + |
| Antigen presentation | + | ++++ |
| Cytokine secretion | Not clear | IL-12, IL-18, IFN-γ, chemokines |
| Location | Peripheral tissue | Secondary lymphoid organs |
The reason for the trade is geographical: a DC must be in peripheral tissue to collect antigen and in a lymph node to present it to naïve T cells. Encountering a pathogen triggers the switch from sampling to reporting.
Marking guide: 1 mark per row. The uptake/presentation reversal is the point of the question and must be explicit.
3
Compare the three professional antigen-presenting cells.
6 marks
| Dendritic cell | Macrophage | B cell | |
|---|---|---|---|
| Antigen uptake | Pinocytosis +++ | Phagocytosis, pinocytosis, receptor-mediated endocytosis +++ | Ig-mediated ++++ |
| MHC expression | Constitutive ++++ | Inducible — by bacteria and cytokines | Constitutive +++ |
| Co-stimulatory (B7) | Constitutive ++++ | Inducible, − to +++ | Inducible, − to +++ |
| Antigens presented | Peptides, viral antigens, allergens | Particulate; intracellular and extracellular pathogens | Soluble antigens, toxins, viruses |
| Location | Widespread | Widespread | Lymphoid tissue, peripheral blood |
| Activates naïve T cells? | Yes | No | No |
The decisive row is co-stimulation. Only the DC is constitutively equipped with both MHC and B7, so only the DC can supply signal 1 and signal 2 to a naïve T cell — the reason it alone initiates a primary response.
Marking guide: 1 mark per row. Naming Ig-mediated uptake for B cells and constitutive B7 for DCs are the two discriminating details.