Inflammation and Repair Practice Questions

Q: Contents of microbicidal granules of leucocytes include all, EXCEPT:

LCAM. The question asks to identify the substance that is **not** a content of microbicidal granules. **1. Why LCAM is the correct answer:** **LCAM (Leucocyte Cell Adhesion Molecule)**, also known as **L-selectin (CD62L)**, is a cell surface glycoprotein, not a granule content. It is located on the plasma membrane of leucocytes and plays a critical role in the initial "rolling" phase of leucocyte extravasation by binding to ligands on the endothelium (GlyCAM-1, CD34). Since it is a structural membrane protein involved in adhesion rather than a secreted microbicidal agent, it is the correct "EXCEPT" choice. **2. Analysis of incorrect options:** * **Elastase (Option A):** Found in the **azurophilic (primary) granules** of neutrophils [1]. It is a potent serine protease that degrades bacterial proteins and extracellular matrix components [1]. * **Major Basic Protein (Option B):** The primary constituent of **eosinophil granules**. It is highly toxic to helminths (parasites) and causes degranulation of mast cells and basophils. * **Eotoxin (Option C):** Likely refers to **Eosinophil-derived neurotoxin (EDN)** or general bactericidal toxins. These are stored in leucocyte granules to neutralize pathogens [1]. **Clinical Pearls for NEET-PG:** * **Neutrophil Granules:** * *Primary (Azurophilic):* Myeloperoxidase (MPO), Defensins, Elastase [1]. * *Secondary (Specific):* Lactoferrin, Lysozyme, Alkaline Phosphatase, Collagenase. * **Selectin Family:** L-selectin (Leucocytes), E-selectin (Endothelium), P-selectin (Platelets/Endothelium). * **Deficiency:** Leukocyte Adhesion Deficiency (LAD) type 1 is a defect in integrins (CD18), while LAD type 2 is a defect in Sialyl-Lewis X (selectin ligand). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 91-92.

Q: Which cytokine possesses pyrogenic activity?

IL-6. **Explanation:** The correct answer is **IL-6**. Fever (pyrexia) is a systemic manifestation of the acute-phase response, primarily mediated by cytokines known as **endogenous pyrogens**. **1. Why IL-6 is correct:** When the body encounters pathogens or toxins, macrophages and other cells release specific cytokines: **IL-1, TNF-α, and IL-6**. These cytokines travel via the bloodstream to the hypothalamus. Here, they stimulate the enzyme **cyclooxygenase (COX)**, which converts arachidonic acid into **Prostaglandin E2 (PGE2)** [1]. PGE2 acts on the thermoregulatory center of the hypothalamus to increase the body’s temperature set-point, resulting in fever. IL-6 is a potent inducer of this process and is also the primary stimulator for the hepatic synthesis of acute-phase proteins (like CRP) [1]. **2. Why the other options are incorrect:** * **TGF-beta (A):** An anti-inflammatory cytokine involved in wound healing, fibrosis, and limiting the immune response. It does not induce fever. * **IL-5 (C):** Primarily responsible for the proliferation, differentiation, and activation of **eosinophils**. It is central to helminthic infections and allergic reactions. * **IL-2 (D):** Known as the T-cell growth factor; it stimulates the proliferation of T-lymphocytes and NK cells. **High-Yield Clinical Pearls for NEET-PG:** * **Major Endogenous Pyrogens:** IL-1, TNF, and IL-6 [1]. * **Exogenous Pyrogen:** Bacterial Lipopolysaccharide (LPS) is the most common example. * **Mechanism of Antipyretics:** Aspirin and NSAIDs reduce fever by inhibiting COX, thereby blocking PGE2 synthesis. * **IL-6 Marker:** It is the chief stimulator of **C-Reactive Protein (CRP)** production in the liver [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 111.

Q: Which of the following is NOT associated with integrins?

Rolling. To master the process of **Leukocyte Extravasation**, it is essential to distinguish between the specific adhesion molecules involved at each step. [1] ### **Why "Rolling" is the Correct Answer** **Rolling** is the initial, transient tethering of leukocytes to the endothelium. [1] This step is mediated by **Selectins** (L-selectin on leukocytes; E and P-selectin on endothelium), not integrins. [1] Selectins have low-affinity interactions that allow the cell to "roll" along the vessel wall under the force of blood flow. [1] ### **Analysis of Other Options** * **Adhesion (B) & Arrest (C):** These steps occur when rolling leukocytes are activated by chemokines, causing a conformational change in **Integrins** (e.g., LFA-1, VLA-4) from a low-affinity to a **high-affinity state**. [1] These integrins bind firmly to ligands like **ICAM-1** and **VCAM-1** on the endothelium, leading to the "arrest" or firm attachment of the cell. [1] * **Transmigration (D):** Also known as diapedesis, this involves leukocytes squeezing through endothelial junctions. While **PECAM-1 (CD31)** is the primary mediator here, certain integrins also facilitate the crawling and squeezing process required to exit the vessel. [1] ### **High-Yield NEET-PG Pearls** * **LAD Type 1:** Caused by a deficiency in **β2-integrins (CD18)**. Clinical hallmark: Delayed separation of the umbilical cord and lack of pus formation. [1] * **LAD Type 2:** Caused by a defect in **Sialyl-Lewis X** (the ligand for Selectins), leading to a defect in **Rolling**. * **Mnemonic:** **S**electins = **S**lowing down (Rolling); **I**ntegrins = **I**mmobilization (Firm Adhesion). * **ICAM-1/VCAM-1** belong to the Immunoglobulin superfamily and act as the "docking stations" for integrins. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 87-89.

Question 1

Contents of microbicidal granules of leucocytes include all, EXCEPT:

Accepted Answer

LCAM

Answer

Elastase

Answer

Major basic protein

Answer

Eotoxin

Question 2

In an experiment, bacteria are inoculated into aliquots of normal human blood treated with an anticoagulant. It is observed that the bacteria are either phagocytized by neutrophils or undergo lysis. Which of the following blood plasma components is most likely to facilitate these effects?

Accepted Answer

Complement

Answer

Fibrin

Answer

Kallikrein

Answer

Plasmin

Question 3

Which of the following is a chemokine?

Accepted Answer

IL-8

Answer

Leukotriene A4

Answer

C5

Answer

C3

Question 4

Which cytokine possesses pyrogenic activity?

Accepted Answer

IL-6

Answer

TGF-beta

Answer

IL-5

Answer

IL-2

Question 5

Abscess formation is particularly characteristic of infections with which of the following microorganisms?

Accepted Answer

Staphylococci

Answer

Viruses

Answer

Rickettsiae

Answer

Streptococci

Question 6

Chemotaxis is mediated by?

Accepted Answer

C5a

Answer

IL-2

Answer

IFN-g

Answer

IL-5

Question 7

Which of the following is NOT associated with integrins?

Accepted Answer

Rolling

Answer

Adhesion

Answer

Arrest

Answer

Transmigration of cells

Question 8

Non-caseating granulomas are seen in which of the following conditions EXCEPT?

Accepted Answer

Metastatic lung carcinoma

Answer

Tuberculosis

Answer

Byssinosis

Answer

Hodgkin's disease

Question 9

Which of the following is the most effective bactericidal mechanism?

Accepted Answer

NADPH oxidase

Answer

Free radicals

Answer

Myeloperoxidase-halide system

Answer

Acid hydrolases

Question 10

What is Zenker's degeneration?

Accepted Answer

Coagulative necrosis

Answer

Liquefactive necrosis

Answer

Fibroid necrosis

Answer

Caseous necrosis

Inflammation and Repair — MCQs

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