Cell-mediated immunity MCQs With Answer

Cell-mediated immunity MCQs With Answer

Cell-mediated immunity is a cornerstone of adaptive immune responses, especially relevant to pharmacists working with immunotherapies, vaccines and transplant medicine. This blog presents a focused set of 20 multiple-choice questions with answers on cell-mediated immunity tailored for M.Pharm students. Questions cover antigen presentation, T-cell subsets, cytotoxic mechanisms, co-stimulation, cytokine networks, immune checkpoints, diagnostic assays and clinical correlations. Each MCQ is designed to test conceptual depth and application, not just recall, helping students prepare for exams and practical therapeutics. Use these questions for self-assessment, group study, or rapid revision; detailed answers reinforce understanding of pathways and lab techniques central to immunotechnology.

Q1. Which pathway primarily presents endogenous (intracellular) antigen peptides to CD8+ T cells?

• Presentation of endogenously synthesized peptides by MHC class I molecules
• Presentation of exogenous antigens by MHC class II molecules after endocytosis
• Presentation of lipid antigens by CD1 molecules exclusively to CD8+ T cells
• Presentation of intact proteins on B-cell surface MHC class II to CD8+ T cells

Correct Answer: Presentation of endogenously synthesized peptides by MHC class I molecules

Q2. Which statement correctly describes the primary restriction and phenotype of cytotoxic T lymphocytes (CTLs)?

• CTLs express CD4 and recognize peptide on MHC class II
• CTLs express CD8 and recognize peptide on MHC class I
• CTLs express CD25 and recognize free antigen without MHC
• CTLs lack TCR and kill targets via antibody-dependent mechanisms only

Correct Answer: CTLs express CD8 and recognize peptide on MHC class I

Q3. Which interaction provides the essential co-stimulatory signal required for naive T-cell activation?

• PD-1 on T cell binding PD-L1 on APC
• CTLA-4 on T cell binding CD80/86 on APC
• CD28 on T cell binding CD80/86 (B7) on APC
• Fas on T cell binding FasL on APC

Correct Answer: CD28 on T cell binding CD80/86 (B7) on APC

Q4. Which cytokine is the prototype Th1 cytokine that activates macrophages and promotes cell-mediated immunity?

• Interleukin-4 (IL-4)
• Interferon-gamma (IFN-γ)
• Interleukin-10 (IL-10)
• Transforming growth factor-beta (TGF-β)

Correct Answer: Interferon-gamma (IFN-γ)

Q5. What is the principal mechanism by which CD8+ CTLs induce apoptosis in target cells?

• Secretion of large amounts of IL-4 to induce apoptosis
• Release of perforin to form pores and granzymes to trigger apoptosis
• Engulfment of target cells by phagocytosis
• Neutralization of surface antigens to block signaling

Correct Answer: Release of perforin to form pores and granzymes to trigger apoptosis

Q6. Natural killer (NK) cells preferentially kill cells that:

• Overexpress MHC class I molecules
• Display high-affinity antibodies on their surface
• Have downregulated MHC class I expression (“missing-self” recognition)
• Present antigen on MHC class II to CD4+ T cells

Correct Answer: Have downregulated MHC class I expression (“missing-self” recognition)

Q7. Th17 cells are most important for which type of immune response?

• Promoting B-cell class switching to IgE
• Recruiting neutrophils and defending mucosal barriers via IL-17
• Suppressing autoimmunity through IL-10 production
• Direct cytotoxic killing of virus-infected cells

Correct Answer: Recruiting neutrophils and defending mucosal barriers via IL-17

Q8. Which combination of markers is characteristic of naturally occurring regulatory T cells (Tregs)?

• CD8+ CD56+ FoxP3-
• CD4+ CD25+ FoxP3+
• CD4- CD8- γδ TCR+
• CD19+ CD25+ IgD+

Correct Answer: CD4+ CD25+ FoxP3+

Q9. What is cross-presentation in the context of antigen presentation?

• Presentation of self-peptides on MHC class II by thymic epithelial cells
• Presentation of exogenous antigens on MHC class I by professional APCs
• Presentation of lipid antigens by CD1 molecules to NKT cells
• Presentation of peptides on MHC class II to CD8+ T cells

Correct Answer: Presentation of exogenous antigens on MHC class I by professional APCs

Q10. Delayed-type hypersensitivity (DTH) reactions are primarily mediated by which cells?

• Immediate IgE-mediated mast cells
• Th1 CD4+ T cells and activated macrophages
• Circulating neutrophils and complement only
• B cells producing IgM antibodies

Correct Answer: Th1 CD4+ T cells and activated macrophages

Q11. CTLA-4 (CD152) downregulates T-cell responses mainly by which mechanism?

• Increasing IL-2 production to exhaust T cells
• Competing with CD28 for binding CD80/86 and delivering inhibitory signals
• Binding peptide-MHC complexes to block TCR recognition
• Directly lysing activated T cells via perforin release

Correct Answer: Competing with CD28 for binding CD80/86 and delivering inhibitory signals

Q12. In transplant immunology, direct allorecognition refers to:

• Recipient APCs presenting processed donor peptides on self-MHC to recipient T cells
• Recipient B cells recognizing donor antibodies
• Donor APCs presenting intact donor MHC-peptide complexes directly to recipient T cells
• NK cells recognizing non-self blood group antigens

Correct Answer: Donor APCs presenting intact donor MHC-peptide complexes directly to recipient T cells

Q13. Antibody-dependent cellular cytotoxicity (ADCC) mediated by NK cells primarily uses which receptor?

• FcγRIII (CD16) binding to IgG-coated targets
• Complement receptor 1 (CR1) binding to C3b-opsonized cells
• Toll-like receptor 4 (TLR4) recognizing LPS-coated cells
• FcεRI binding to IgE-coated targets

Correct Answer: FcγRIII (CD16) binding to IgG-coated targets

Q14. Which laboratory assay is classically used to quantify cytotoxic T-lymphocyte (CTL) killing of target cells?

• ELISA for circulating antibodies
• Chromium-51 (51Cr) release assay measuring target cell lysis
• Western blot for granzyme expression in serum
• Flow cytometric CD19 enumeration

Correct Answer: Chromium-51 (51Cr) release assay measuring target cell lysis

Q15. The T-cell receptor (TCR) complex transduces activation signals through which associated molecules?

• CD3 complex (CD3γ, CD3δ, CD3ε) and ζ chains associated with the TCR
• Fc receptors directly linked to TCR alpha-beta
• BCR signaling molecules Igα and Igβ
• MHC class I molecules providing intrinsic kinase activity

Correct Answer: CD3 complex (CD3γ, CD3δ, CD3ε) and ζ chains associated with the TCR

Q16. Which phenotype is characteristic of central memory T cells (Tcm) compared with effector memory T cells (Tem)?

• Tcm express CCR7 and L-selectin allowing lymph node homing
• Tcm lack IL-2 production and are terminally differentiated
• Tcm are CD8- and only found in mucosal tissues
• Tcm constitutively secrete high levels of perforin

Correct Answer: Tcm express CCR7 and L-selectin allowing lymph node homing

Q17. Superantigens cause massive T-cell activation by which mechanism?

• Processing into peptides that bind deep in the MHC groove selectively
• Cross-linking the variable region of the TCR β-chain with MHC class II outside the peptide groove
• Specifically activating only regulatory T cells to suppress immunity
• Blocking TAP transport to prevent antigen presentation

Correct Answer: Cross-linking the variable region of the TCR β-chain with MHC class II outside the peptide groove

Q18. Interleukin-2 (IL-2) primarily functions in cell-mediated immunity to:

• Directly kill infected cells via complement activation
• Promote T-cell proliferation, survival and differentiation after activation
• Induce class switching to IgE in B cells
• Neutralize bacterial toxins in serum

Correct Answer: Promote T-cell proliferation, survival and differentiation after activation

Q19. Gamma-delta (γδ) T cells differ from conventional αβ T cells in that they:

• Require antigen presentation exclusively on MHC class II
• Recognize a broad range of non-peptide and stress-induced ligands without strict MHC restriction
• Are functionally identical to B cells and produce antibody
• Express CD19 and participate in germinal center reactions

Correct Answer: Recognize a broad range of non-peptide and stress-induced ligands without strict MHC restriction

Q20. The ELISPOT assay is most useful in cell-mediated immunity studies because it:

• Quantifies single cells secreting specific cytokines, such as IFN-γ
• Measures serum antibody concentrations in bulk
• Detects complement activation fragments in plasma
• Assesses DNA mutations in TCR genes

Correct Answer: Quantifies single cells secreting specific cytokines, such as IFN-γ

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