Chapter 26 — Quiz

Twenty-two items. Answer key at the end. Several items have a deliberately attractive wrong option; if you are drawn to it, read the explanation rather than just noting the letter.

1. What does a T-cell receptor actually contact?

A. An intact folded protein on a pathogen's surface B. A short peptide held in the groove of an MHC/HLA molecule C. A carbohydrate on a bacterial cell wall D. A free-floating antigen in serum

2. Class I HLA molecules present peptides derived from:

A. Material engulfed from outside the cell B. Proteins made inside the cell C. Only viral proteins D. Only mutated proteins

3. Which cell type recognizes peptides presented on class II?

A. CD8 cytotoxic T cells B. CD4 helper T cells C. Natural killer cells D. Plasma cells

4. Most antibody epitopes on natural proteins are:

A. Linear B. Conformational C. Carbohydrate D. Identical to T-cell epitopes

5. The main reason short peptides make poor prophylactic vaccines against most pathogens is:

A. They are too expensive to manufacture B. They cannot be stored C. Protection usually depends on antibodies, which read conformational surfaces that a short peptide presents poorly D. They are destroyed by the proteasome

6. "HLA restriction" means:

A. Some people cannot mount immune responses at all B. A T cell recognizes its peptide only in the context of a particular HLA molecule C. HLA molecules restrict how much antigen can enter a cell D. Vaccines must be refrigerated

7. The HLA genes are notable because they are:

A. Present only in humans B. Identical in all members of a species C. The most polymorphic genes in the human genome D. Not inherited

8. A peptide vaccine produces a robust response in one person and nothing detectable in another. The explanation this chapter emphasizes most is:

A. The second person's immune system is weaker B. The second person's HLA molecules may not present that peptide at all C. The second person received a lower dose D. The peptide degraded before injection

9. Why is an adjuvant usually essential for a peptide vaccine?

A. It keeps the peptide from dissolving B. It supplies the innate danger signal without which antigen exposure tends to produce anergy or tolerance rather than immunity C. It increases the peptide's molecular weight above the protein threshold D. It prevents anaphylaxis

10. A T cell that encounters its peptide without costimulation typically:

A. Becomes a long-lived memory cell B. Becomes anergic, is deleted, or becomes regulatory C. Kills the presenting cell D. Switches to making antibodies

11. A neoantigen is:

A. Any protein overexpressed by a tumor B. A peptide containing an amino acid change from a somatic mutation, absent from the normal proteome C. A synthetic peptide designed by an algorithm D. Any antigen not previously described in the literature

12. The key immunological advantage of neoantigens over tumor-associated antigens is:

A. They are easier to synthesize B. They are present in more patients C. They are not subject to central tolerance, so the high-affinity repertoire against them is intact D. They do not require HLA presentation

13. In the individualized vaccine pipeline, sequencing normal tissue is required in order to:

A. Confirm the patient's identity B. Establish which sequence changes are somatic rather than inherited C. Measure immune function D. Determine the dose

14. Synthetic long peptides (roughly 20–30 residues) are preferred over minimal 8–10-residue epitopes largely because:

A. They are cheaper B. They bind HLA more tightly C. They must be processed by professional presenting cells, avoiding tolerizing direct loading onto cells that cannot costimulate D. They last longer in circulation

15. An mRNA cancer vaccine is best described as:

A. A peptide drug B. Not a peptide drug, but a peptide-antigen vaccine — the message is still a peptide sequence C. A gene therapy that permanently alters the genome D. A small-molecule immunostimulant

16. The main practical reason individualized programs reached for mRNA rather than peptides is:

A. mRNA is more immunogenic in every case B. One construct encoding many epitopes requires one synthesis, which is far more standardizable than manufacturing many individual peptides per patient C. mRNA does not require an adjuvant of any kind D. Peptides cannot encode more than one epitope

17. As of 2026, the status of individualized neoantigen cancer vaccines is:

A. Approved for general use in melanoma B. Abandoned after phase 3 failures C. In randomized trials, with encouraging early results supporting larger confirmatory trials, and no general approval anywhere D. Available by prescription in most countries

18. The attribution problem in current cancer vaccine trials arises because:

A. Patients are not told which arm they are in B. The vaccines are given alongside checkpoint inhibitors, which are themselves effective C. Recurrence cannot be measured D. Neoantigens cannot be verified

19. In a small single-arm study, patients who mounted a vaccine-induced T-cell response remained recurrence-free longer than those who did not. The correct reading is:

A. The vaccine works B. The vaccine works in immune-competent patients only C. This is a responder-versus-non-responder comparison, not a randomized one, and it motivates a randomized trial rather than establishing benefit D. The vaccine has been disproven

20. The most successful "cancer vaccines" currently in existence are:

A. Therapeutic peptide vaccines in melanoma B. Prophylactic antiviral vaccines against hepatitis B and human papillomavirus C. Autologous cellular immunotherapies D. Oncolytic viruses

21. Peptide-based allergy immunotherapy aims to:

A. Provoke a strong cytotoxic response against the allergen B. Induce tolerance using peptides too small to cross-link IgE and trigger mast cells C. Replace antihistamines D. Remove IgE from circulation

22. This chapter rates individualized neoantigen cancer vaccines 🔬 rather than ⚠️ principally because:

A. The mechanism is unproven B. There is no human data of any kind C. The randomized evidence is early and narrow, the intervention is a manufacturing process rather than a fixed molecule, and no confirmatory trial has established durable benefit D. The approach is implausible