Understanding the mechanism of inflammation – migration of WBCs MCQs With Answer is essential for B. Pharm students preparing for exams in pharmacology, pathology, and clinical pharmacy. This clear, concise introduction covers cellular and molecular steps of leukocyte trafficking during acute and chronic inflammation: endothelial activation, selectin‑mediated rolling, integrin activation and inside‑out signaling, firm adhesion, transmigration (diapedesis), and chemotaxis driven by chemokines, complement fragments (C5a), and eicosanoids (LTB4). It highlights clinical correlations, leukocyte adhesion deficiencies, reactive oxygen species, NETs, and therapeutic targets such as corticosteroids, NSAIDs, colchicine, and integrin antagonists. Practice MCQs emphasize mechanisms, signaling pathways, and lab findings to strengthen exam readiness. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the initial molecular event that mediates leukocyte capture and slowing on activated endothelium?
- Selectin-mediated rolling
- Integrin-mediated firm adhesion
- Phagocytosis
- Cytokine secretion
Correct Answer: Selectin-mediated rolling
Q2. Selectins primarily facilitate which step of leukocyte recruitment?
- Phagocytosis of microbes
- Rolling along the endothelium
- Transendothelial migration
- Opsonization
Correct Answer: Rolling along the endothelium
Q3. Which carbohydrate ligand on leukocytes binds to selectins during rolling?
- ICAM-1
- sialyl Lewis X
- PECAM-1
- VCAM-1
Correct Answer: sialyl Lewis X
Q4. Activation of leukocyte integrins during adhesion is primarily achieved by which mechanism?
- Outside-in signaling only
- Inside-out signaling that increases integrin affinity
- Proteolytic cleavage of integrins
- Direct binding of chemokines to ICAM-1
Correct Answer: Inside-out signaling that increases integrin affinity
Q5. Which molecule is critical for leukocyte transmigration between endothelial cells?
- Fibrinogen
- PECAM-1 (CD31)
- E-selectin
- Complement C3b
Correct Answer: PECAM-1 (CD31)
Q6. Which complement-derived mediator is a potent chemotactic factor for neutrophils?
- C3b
- C5a
- C1q
- C9
Correct Answer: C5a
Q7. The term “diapedesis” describes which process?
- Apoptosis of leukocytes
- Transmigration of leukocytes across endothelium
- Generation of reactive oxygen species
- Aggregation of platelets
Correct Answer: Transmigration of leukocytes across endothelium
Q8. Leukocyte adhesion deficiency type 1 (LAD1) is caused by a defect in which molecule?
- CD18 (β2 integrin)
- E-selectin
- PECAM-1
- von Willebrand factor
Correct Answer: CD18 (β2 integrin)
Q9. Which selectin is stored in platelet alpha granules and endothelial Weibel-Palade bodies and appears on the surface after activation?
- L-selectin
- E-selectin
- P-selectin
- Vascular selectin
Correct Answer: P-selectin
Q10. Firm adhesion of leukocytes to endothelium is mediated by interactions between which pairs?
- Selectins and sialyl Lewis X
- Integrins (e.g., LFA-1) and ICAM-1
- Complement C3 and C3b receptor
- Histamine and H1 receptor
Correct Answer: Integrins (e.g., LFA-1) and ICAM-1
Q11. Which cytokine is a major inducer of endothelial adhesion molecules such as ICAM-1 and VCAM-1?
- Interferon-alpha
- TNF-alpha
- IL-4
- IL-10
Correct Answer: TNF-alpha
Q12. Which receptor family mediates leukocyte chemotaxis in response to chemokines like IL-8?
- Toll-like receptors
- G-protein coupled chemokine receptors (e.g., CXCR1)
- Tyrosine kinase receptors
- Nuclear hormone receptors
Correct Answer: G-protein coupled chemokine receptors (e.g., CXCR1)
Q13. Which enzyme complex generates superoxide during the respiratory burst in neutrophils?
- Myeloperoxidase
- NADPH oxidase
- Catalase
- Superoxide dismutase
Correct Answer: NADPH oxidase
Q14. Deficiency of which enzyme is associated with an increased risk of Candida infections due to impaired HOCl production?
- NADPH oxidase
- Myeloperoxidase
- MPO-related peroxidase
- Glucose-6-phosphate dehydrogenase
Correct Answer: Myeloperoxidase
Q15. Neutrophil extracellular traps (NETs) are composed mainly of which components?
- Lipid micelles and prostaglandins
- DNA, histones and granular proteins
- Integrins and selectins
- Collagen and elastase
Correct Answer: DNA, histones and granular proteins
Q16. Which of the following are classical opsonins that enhance phagocytosis?
- TNF-alpha and IL-1
- IgG and C3b
- Histamine and bradykinin
- PGE2 and LTB4
Correct Answer: IgG and C3b
Q17. Which mediator causes rapid endothelial cell contraction and increased vascular permeability in acute inflammation?
- IL-10
- Histamine
- Interferon-gamma
- Transforming growth factor-beta
Correct Answer: Histamine
Q18. The predominant route for leukocyte transmigration across endothelium is:
- Transcellular through endothelial cytoplasm
- Paracellular between endothelial junctions
- Across basement membrane without junctional disruption
- Via direct passage through platelets
Correct Answer: Paracellular between endothelial junctions
Q19. Platelet-activating factor (PAF) contributes to leukocyte recruitment by which actions?
- Inhibiting integrin activation
- Promoting leukocyte adhesion, chemotaxis and degranulation
- Blocking selectin expression
- Acting as an anti-inflammatory cytokine
Correct Answer: Promoting leukocyte adhesion, chemotaxis and degranulation
Q20. Which leukotriene is a potent neutrophil chemoattractant produced via 5-lipoxygenase?
- LTC4
- LTB4
- PGE2
- TXA2
Correct Answer: LTB4
Q21. Which class of drugs reduces leukocyte recruitment by decreasing cytokine synthesis and adhesion molecule expression?
- Beta-blockers
- Statins
- Corticosteroids
- Loop diuretics
Correct Answer: Corticosteroids
Q22. Complement activation results in generation of which enzyme complex that cleaves C5 to produce C5a?
- C3 convertase
- C5 convertase
- Membrane attack complex
- Factor B
Correct Answer: C5 convertase
Q23. A clinical sign of leukocyte adhesion deficiency (LAD) in newborns is:
- Early umbilical cord separation
- Delayed separation of the umbilical cord
- Excessive bleeding due to platelet dysfunction
- Hyperresponsiveness to vaccines
Correct Answer: Delayed separation of the umbilical cord
Q24. ICAM-1 and VCAM-1 belong to which family of adhesion molecules?
- Selectin family
- Integrin family
- Immunoglobulin superfamily
- C-type lectin family
Correct Answer: Immunoglobulin superfamily
Q25. Chemotactic receptors detect gradients and signal through which intracellular pathway to direct movement?
- cAMP-dependent nuclear receptors
- G-protein coupled receptor signaling and actin cytoskeleton rearrangement
- Direct DNA binding transcription factors
- Tyrosine kinase phosphorylation of histones
Correct Answer: G-protein coupled receptor signaling and actin cytoskeleton rearrangement
Q26. The first reactive species formed by NADPH oxidase during respiratory burst is:
- Hydrogen peroxide (H2O2)
- Superoxide anion (O2−)
- Hypochlorous acid (HOCl)
- Hydroxyl radical (•OH)
Correct Answer: Superoxide anion (O2−)
Q27. Which selectin is induced on endothelium by cytokines such as TNF and IL-1?
- L-selectin
- E-selectin
- P-selectin
- S-selectin
Correct Answer: E-selectin
Q28. The leukocyte integrin LFA-1 corresponds to which CD designation?
- CD11a/CD18
- CD3/CD4
- CD28/CD86
- CD19/CD21
Correct Answer: CD11a/CD18
Q29. Which prostaglandin contributes to vasodilation and sensitization of pain receptors in inflammation?
- TXA2
- PGE2
- LTB4
- PGE1
Correct Answer: PGE2
Q30. Which chemokine is the prototypic neutrophil chemoattractant produced by macrophages and endothelium?
- CCL2 (MCP-1)
- CXCL8 (IL-8)
- RANTES (CCL5)
- SDF-1 (CXCL12)
Correct Answer: CXCL8 (IL-8)
Q31. Which acute phase protein is most widely used as a sensitive clinical marker of inflammation?
- Albumin
- C-reactive protein (CRP)
- Transferrin
- Fibrinogen
Correct Answer: C-reactive protein (CRP)
Q32. Chronic granulomatous inflammation with formation of granulomas is classically associated with which pathogen?
- Streptococcus pyogenes
- Mycobacterium tuberculosis
- Escherichia coli
- Vibrio cholerae
Correct Answer: Mycobacterium tuberculosis
Q33. Which endothelial junctional protein helps maintain cell-cell contacts and must be reorganized for leukocyte extravasation?
- Claudin
- Occludin
- VE-cadherin
- Desmoglein
Correct Answer: VE-cadherin
Q34. Which leukocyte predominates in the early (first 24–48 hours) phase of acute inflammation?
- Lymphocytes
- Eosinophils
- Neutrophils
- Plasma cells
Correct Answer: Neutrophils
Q35. Monocyte differentiation into tissue macrophages is mainly stimulated by which colony-stimulating factor?
- G-CSF
- GM-CSF
- M-CSF (CSF-1)
- EPO
Correct Answer: M-CSF (CSF-1)
Q36. The chemotactic activity of leukotrienes is inhibited by blocking which enzyme?
- Cyclooxygenase (COX)
- 5-lipoxygenase (5-LOX)
- Phospholipase A2
- Thromboxane synthase
Correct Answer: 5-lipoxygenase (5-LOX)
Q37. A negative nitroblue tetrazolium (NBT) test is indicative of a defect in which pathway?
- MPO-H2O2-halide system
- NADPH oxidase respiratory burst
- Complement classical pathway
- Phagolysosomal acidification
Correct Answer: NADPH oxidase respiratory burst
Q38. Which endothelial ligand binds leukocyte integrins during firm adhesion?
- Sialyl Lewis X
- ICAM-1
- Fibrin
- Histamine
Correct Answer: ICAM-1
Q39. A deficiency in sialyl Lewis X would impair which step of leukocyte recruitment?
- Firm adhesion via integrins
- Rolling mediated by selectins
- Transmigration through basement membrane
- Phagolysosomal killing
Correct Answer: Rolling mediated by selectins
Q40. Upregulation of E-selectin on endothelium is primarily induced by which mediators?
- IL-1 and TNF-alpha
- IL-10 and TGF-beta
- Histamine and serotonin
- IFN-alpha and IFN-beta
Correct Answer: IL-1 and TNF-alpha
Q41. Bacterial N-formylated peptides (fMLP) act as chemoattractants by binding to which target on neutrophils?
- Toll-like receptor 4
- Formyl peptide G-protein coupled receptors
- Complement receptor 3
- Fc gamma receptor
Correct Answer: Formyl peptide G-protein coupled receptors
Q42. The leukocyte integrin VLA-4 (alpha4beta1) primarily binds to which endothelial ligand?
- ICAM-1
- VCAM-1
- E-selectin
- Collagen IV
Correct Answer: VCAM-1
Q43. Which enzyme in azurophilic granules catalyzes formation of hypochlorous acid from H2O2?
- Lysozyme
- Elastase
- Myeloperoxidase
- Collagenase
Correct Answer: Myeloperoxidase
Q44. A marked neutrophilia with a “left shift” is most suggestive of which clinical scenario?
- Acute bacterial infection
- Chronic viral infection
- Allergic reaction
- Parasitic infestation
Correct Answer: Acute bacterial infection
Q45. Which cytokine has prominent anti-inflammatory effects and can reduce leukocyte recruitment?
- IL-1
- IL-6
- IL-10
- TNF-alpha
Correct Answer: IL-10
Q46. Which drug specifically inhibits 5-lipoxygenase and reduces leukotriene synthesis?
- Zileuton
- Ibuprofen
- Aspirin
- Indomethacin
Correct Answer: Zileuton
Q47. Which complement fragment functions as an opsonin to enhance phagocytosis?
- C5a
- C3b
- C4a
- C6
Correct Answer: C3b
Q48. The Weibel-Palade bodies of endothelial cells store which mediator involved in hemostasis and leukocyte recruitment?
- ICAM-1
- von Willebrand factor and P-selectin
- TNF-alpha
- Prostacyclin
Correct Answer: von Willebrand factor and P-selectin
Q49. Endothelial surface P-selectin translocation to the membrane is rapidly induced by release from which storage organelle?
- Golgi apparatus
- Weibel-Palade bodies
- Lysosomes
- Peroxisomes
Correct Answer: Weibel-Palade bodies
Q50. Which monoclonal antibody targets alpha4-integrin and is used to block leukocyte adhesion in multiple sclerosis and Crohn’s disease?
- Infliximab
- Adalimumab
- Natalizumab
- Rituximab
Correct Answer: Natalizumab
