Screening for immunomodulators, immunosuppressants and immunostimulants MCQs With Answer

Introduction: This collection of MCQs on screening for immunomodulators, immunosuppressants and immunostimulants is tailored for M.Pharm students studying Pharmacological and Toxicological Screening Methods-I. The questions emphasize both in vitro and in vivo assays, mechanistic principles, relevant biomarkers and standard models used to evaluate immune modulation. Expect items covering humoral and cell-mediated immunity assays, macrophage and neutrophil function tests, cytokine-based readouts, antigen-specific responses, and commonly used positive controls and limitations of each method. These MCQs aim to deepen conceptual understanding and prepare you for practical and theoretical examinations by focusing on assay selection, interpretation of outcomes, and translational relevance.

Q1. Which assay directly measures the ability of B cells to produce antibody-secreting cells against a specific antigen?

• Plaque-forming cell (PFC) assay
• Carbon clearance test
• Neutrophil adhesion test
• Delayed-type hypersensitivity (DTH) assay

Correct Answer: Plaque-forming cell (PFC) assay

Q2. The carbon clearance assay primarily assesses which immune function?

• Reticuloendothelial system (macrophage) phagocytic activity
• T cell proliferative capacity
• Humoral antibody affinity
• Nitroblue tetrazolium reduction in neutrophils

Correct Answer: Reticuloendothelial system (macrophage) phagocytic activity

Q3. Which in vitro assay is commonly used to quantify lymphocyte proliferation in response to mitogens?

• MTT or BrdU incorporation assay
• Hemagglutination inhibition test
• Carbon clearance
• Contact hypersensitivity

Correct Answer: MTT or BrdU incorporation assay

Q4. The cyclophosphamide-induced neutropenia model is primarily used to screen for what property of a compound?

• Immunostimulatory potential (ability to restore leukocyte counts)
• Direct macrophage phagocytosis inhibition
• Complement activation
• Topical irritancy

Correct Answer: Immunostimulatory potential (ability to restore leukocyte counts)

Q5. Which test evaluates cell-mediated immunity by measuring ear or footpad swelling after antigen re-exposure?

• Delayed-type hypersensitivity (DTH) assay
• Plaque-forming cell (PFC) assay
• Complement fixation test
• Mixed lymphocyte reaction (MLR)

Correct Answer: Delayed-type hypersensitivity (DTH) assay

Q6. In the hemagglutination assay for humoral immunity, what is the primary readout?

• Highest serum dilution causing visible agglutination of erythrocytes
• Number of macrophages ingesting carbon particles
• Percent reduction of neutrophil oxidative burst
• Footpad thickness increase in millimeters

Correct Answer: Highest serum dilution causing visible agglutination of erythrocytes

Q7. The Mixed Lymphocyte Reaction (MLR) is mainly used to assess which immunological interaction?

• Alloreactive T cell proliferation in response to foreign MHC
• Complement-dependent cytotoxicity of antibodies
• Natural killer (NK) cell killing of tumor cells
• B cell isotype switching

Correct Answer: Alloreactive T cell proliferation in response to foreign MHC

Q8. Which assay measures reactive oxygen species production by neutrophils as a marker of innate immune activation?

• Nitroblue tetrazolium (NBT) reduction test
• Plaque-forming cell assay
• Hemagglutination titer
• Contact hypersensitivity assay

Correct Answer: Nitroblue tetrazolium (NBT) reduction test

Q9. ELISPOT assay is especially useful because it can:

• Detect cytokine secretion at the single-cell level
• Measure whole-animal phagocytic index
• Assess complement lytic activity in serum
• Quantify ear swelling after antigen challenge

Correct Answer: Detect cytokine secretion at the single-cell level

Q10. Which of the following is the best positive control for immunosuppression studies in experimental animal models?

• Cyclophosphamide (standard immunosuppressant)
• Lipopolysaccharide (LPS)
• Phytohemagglutinin (PHA)
• Carbon particles

Correct Answer: Cyclophosphamide (standard immunosuppressant)

Q11. Flow cytometry immunophenotyping in immunomodulatory screening is primarily used to:

• Quantify and characterize leukocyte subpopulations and activation markers
• Measure complement activation in serum samples
• Detect antibody titers by agglutination
• Assess in vivo paw edema

Correct Answer: Quantify and characterize leukocyte subpopulations and activation markers

Q12. The in vivo model in which a foreign graft is transplanted to evaluate rejection delay measures the efficacy of:

• Immunosuppressant agents to prevent graft rejection
• Adjuvant activity of compounds
• Humoral antibody affinity maturation
• Oxidative burst in neutrophils

Correct Answer: Immunosuppressant agents to prevent graft rejection

Q13. In screening for immunostimulants, which parameter would indicate enhanced innate immunity?

• Increased macrophage phagocytosis and respiratory burst
• Reduced antibody titers in hemagglutination assay
• Prolonged graft survival time without immunosuppression
• Decreased lymphocyte proliferation to mitogens

Correct Answer: Increased macrophage phagocytosis and respiratory burst

Q14. Which assay is most appropriate to detect cytotoxic T lymphocyte (CTL) mediated killing of target cells in vitro?

• 51Cr-release or LDH-release cytotoxicity assay
• Carbon clearance test
• Hemagglutination assay
• Nitroblue tetrazolium reduction

Correct Answer: 51Cr-release or LDH-release cytotoxicity assay

Q15. When evaluating a candidate immunomodulator, the Selectivity Index (SI) is used to compare:

• Cytotoxicity to immune cells versus therapeutic immune activity
• MHC expression levels across tissues
• Phagocytic index before and after treatment
• Antibody isotype switching from IgM to IgG

Correct Answer: Cytotoxicity to immune cells versus therapeutic immune activity

Q16. Which cytokine measurement technique provides quantitative concentration data in serum or culture supernatants and is widely used in screening?

• Enzyme-linked immunosorbent assay (ELISA)
• Western blot of whole blood
• Plaque-forming cell assay
• Carbon clearance test

Correct Answer: Enzyme-linked immunosorbent assay (ELISA)

Q17. Which screening approach would best detect early innate immune activation by a novel adjuvant in vitro?

• TLR reporter cell lines measuring NF-κB or cytokine promoter activation
• Plaque-forming cell assay for antibody-producing B cells
• Mixed lymphocyte reaction for alloreactivity
• Delayed-type hypersensitivity in mice

Correct Answer: TLR reporter cell lines measuring NF-κB or cytokine promoter activation

Q18. A limitation of the hemagglutination antibody titer assay compared to ELISA is:

• Lower sensitivity and inability to distinguish antibody isotypes precisely
• Requires radioactive isotopes
• Measures single-cell cytokine production only
• Cannot be used in animal models

Correct Answer: Lower sensitivity and inability to distinguish antibody isotypes precisely

Q19. The neutrophil adhesion test assesses immunomodulatory effects by measuring:

• Percentage of neutrophils that adhere to nylon fibers or substrates, reflecting activation
• Serum complement hemolytic units
• Antigen-specific T cell cytotoxicity
• Number of antibody-secreting cells in the spleen

Correct Answer: Percentage of neutrophils that adhere to nylon fibers or substrates, reflecting activation

Q20. For translational relevance when screening immunomodulators, which combination of assays gives a balanced assessment of humoral, cellular and innate responses?

• Hemagglutination (humoral), DTH or MLR (cellular), and carbon clearance or NBT (innate)
• Only ELISA for all cytokines
• Carbon clearance, hemagglutination, and contact irritancy testing only
• Plaque assay, 51Cr-release, and liver enzyme tests only

Correct Answer: Hemagglutination (humoral), DTH or MLR (cellular), and carbon clearance or NBT (innate)

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