Inflammation and Repair Practice Questions

Q: Which is the most potent chemoattractant?

Leukotriene B4. **Explanation:** The correct answer is **Leukotriene B4 (LTB4)**. **1. Why LTB4 is the correct answer:** Leukotrienes are products of the **5-lipoxygenase pathway** of arachidonic acid metabolism. LTB4 is specifically synthesized by neutrophils and macrophages [1]. It is one of the most potent **chemoattractants** known in the inflammatory process [1]. Its primary functions include: * Stimulating neutrophil adhesion to the endothelium. * Promoting **chemotaxis** (directed movement of leukocytes toward the site of injury) [1]. * Inducing the generation of Reactive Oxygen Species (ROS) and the release of lysosomal enzymes. **2. Why the other options are incorrect:** * **Leukotriene C4, D4, and E4:** These are collectively known as **cysteinyl-containing leukotrienes** (or the "Slow Reacting Substance of Anaphylaxis" - SRS-A). Their primary roles are not chemotaxis, but rather: * Potent **vasoconstriction** [1]. * Increased **vascular permeability** (significantly more potent than histamine) [1]. * **Bronchospasm**, making them central to the pathogenesis of bronchial asthma. **3. NEET-PG High-Yield Pearls:** * **Other potent chemoattractants to remember:** Complement component **C5a**, Bacterial products (e.g., **N-formyl methionine** peptides), and Chemokines (specifically **IL-8**). * **Lipoxins:** Unlike leukotrienes, lipoxins (LXA4, LXB4) act as **inhibitors** of inflammation and chemotaxis, serving as "stop signals." * **Zileuton** is a drug that inhibits 5-lipoxygenase, while **Montelukast** blocks leukotriene receptors (C4/D4/E4), highlighting the clinical importance of this pathway in asthma management. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 93-96.

Q: Which of the following is found in secondary granules of neutrophils?

Lactoferrin. Neutrophils (Polymorphonuclear leukocytes) contain two main types of granules essential for their microbicidal activity: **Primary (Azurophilic)** and **Secondary (Specific)** granules. [1] **Why Lactoferrin is Correct:** Secondary granules are the most numerous and contain substances that help in both killing pathogens and tissue remodeling. **Lactoferrin** is a key component of these granules; it acts as a bacteriostatic agent by sequestering free iron, which is essential for bacterial growth and metabolism. Other contents of secondary granules include Vitamin B12-binding protein, Lysozyme, and Collagenase. **Analysis of Incorrect Options:** * **A. Catalase:** This is an antioxidant enzyme primarily found in **Peroxisomes**, not in neutrophil granules. It protects cells from oxidative damage by breaking down hydrogen peroxide. * **B. Gangliosidase:** This is a lysosomal enzyme involved in the degradation of gangliosides. Deficiencies in such enzymes lead to lysosomal storage diseases (e.g., Tay-Sachs). * **C. Proteolytic enzymes:** While neutrophils do contain proteases, major proteolytic enzymes like **Elastase** and **Cathepsin G** are characteristic of **Primary (Azurophilic) granules**, which are essentially modified lysosomes. **High-Yield Facts for NEET-PG:** * **Primary Granules:** Contain Myeloperoxidase (MPO), Defensins, and Acid Hydrolases. MPO is the marker for primary granules. * **Secondary Granules:** Contain Lactoferrin, Alkaline Phosphatase, and NADPH oxidase components. * **Clinical Correlation:** In **Chediak-Higashi Syndrome**, there is a defect in vesicle trafficking leading to giant azurophilic granules and impaired chemotaxis. * **Leukocyte Alkaline Phosphatase (LAP) Score:** This is based on the alkaline phosphatase found in secondary granules; it is elevated in leukemoid reactions but decreased in Chronic Myeloid Leukemia (CML). [1]

Q: What is the most important cytokine responsible for the synthesis of acute phase proteins?

IL-6. **Explanation:** **Correct Option: B (IL-6)** Interleukin-6 (IL-6) is the primary and most potent inducer of **acute-phase protein (APP)** synthesis by hepatocytes in the liver [1]. During inflammation, macrophages and other cells release cytokines that travel to the liver. IL-6 binds to its receptors on hepatocytes, activating the **JAK-STAT signaling pathway**, which leads to the transcription of genes for proteins like C-reactive protein (CRP), Fibrinogen, and Serum Amyloid A (SAA) [1]. While other cytokines contribute, IL-6 is considered the "chief" mediator of this systemic response. **Incorrect Options:** * **IL-1 & TNF-alpha:** These are "upstream" pro-inflammatory cytokines [1]. While they can stimulate the production of certain APPs and induce IL-6, their primary roles are in activating endothelium, inducing fever (via prostaglandin E2), and causing systemic manifestations like shock or cachexia [2]. * **IL-11:** This is a member of the IL-6 family and can stimulate APP synthesis, but its physiological contribution is significantly less than that of IL-6. It is clinically more relevant for its role in stimulating megakaryocytopoiesis (platelet production). **High-Yield Clinical Pearls for NEET-PG:** * **Positive APPs (Increase):** CRP (most sensitive), Fibrinogen (causes high ESR), Ferritin, Haptoglobin, and Complement proteins (C3, C4) [1]. * **Negative APPs (Decrease):** Albumin, Transferrin, and Transthyretin (Pre-albumin). * **ESR vs. CRP:** CRP rises and falls more rapidly than ESR, making it a better marker for acute changes. * **Hepcidin:** An acute-phase reactant induced by IL-6 that sequesters iron, leading to **Anemia of Chronic Disease**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 111. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 101.

Question 1

Which granulomatous condition is associated with hypercalcemia?

Accepted Answer

Systemic Lupus Erythematosus

Answer

Tuberculosis

Answer

Sarcoidosis

Answer

Berylliosis

Question 2

Which product of arachidonic acid metabolism has anti-inflammatory properties?

Accepted Answer

Lipoxin

Answer

Prostacyclin

Answer

TGF-beta

Answer

Leukotrienes

Question 3

A 49-year-old female presents with shortness of breath and hilar lymphadenopathy on chest x-ray. Biopsy of a lymph node reveals granulomas, highly suggestive of sarcoidosis. Which of the following histological findings must be present in the biopsy material to support the diagnosis of granulomatous inflammation?

Accepted Answer

Epithelioid histiocytes

Answer

Asteroid bodies

Answer

Caseous necrosis

Answer

Fibroblast proliferation

Question 4

A 16-year-old boy sustained blunt trauma to his abdomen. Peritoneal lavage shows a hemoperitoneum, and at laparotomy, a portion of the injured liver is removed. Two months later, a CT scan of the abdomen shows that the liver has nearly regained its size before the injury. Which of the following processes best explains this finding?

Accepted Answer

Hyperplasia

Answer

Apoptosis

Answer

Dysplasia

Answer

Hydropic change

Question 5

Which is the most potent chemoattractant?

Accepted Answer

Leukotriene B4

Answer

Leukotriene C4

Answer

Leukotriene D4

Answer

Leukotriene E4

Question 6

Which of the following is found in secondary granules of neutrophils?

Accepted Answer

Lactoferrin

Answer

Catalase

Answer

Gangliosidase

Answer

Proteolytic enzyme

Question 7

What is the most important cytokine responsible for the synthesis of acute phase proteins?

Accepted Answer

IL-6

Answer

IL-1

Answer

IL-11

Answer

TNF alpha

Question 8

What is a disadvantage of somatic stem cells?

Accepted Answer

Limited pluripotency

Answer

Limited availability

Answer

Poor expansion in vitro

Answer

Ethical concerns

Question 9

In genetic deficiency of myeloperoxidase (MPO), the increased susceptibility to infection is due to:

Accepted Answer

Inability to produce hydroxyl halide radicals

Answer

Defective production of prostaglandins

Answer

Defective rolling of neutrophils

Answer

Inability to produce hydrogen peroxide

Question 10

What is the most important mediator of chemotaxis among the following?

Accepted Answer

C5a

Answer

C3b

Answer

C567

Answer

C2

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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