Inflammation and Repair Practice Questions

Q: What is the primary role of IL-1?

T lymphocyte activation. **Explanation:** Interleukin-1 (IL-1) is a key pro-inflammatory cytokine produced primarily by activated macrophages. Its primary role in the immune response is the **activation of T lymphocytes** [1]. When an antigen is presented by an Antigen-Presenting Cell (APC), IL-1 acts as a co-stimulatory signal that induces T cells to produce IL-2 and express IL-2 receptors, leading to T-cell proliferation and clonal expansion [1]. **Analysis of Options:** * **A (Correct):** IL-1 promotes the transition of T cells from the $G_0$ to the $G_1$ phase of the cell cycle, facilitating their activation and cytokine production [1]. * **B (Incorrect):** While chronic inflammation can impair healing, IL-1 actually promotes the early phases of repair by stimulating fibroblast proliferation and collagen synthesis. * **C (Incorrect):** While IL-1 contributes to the inflammatory milieu that sensitizes nociceptors (via prostaglandin induction), it is not its *primary* physiological role compared to immune cell activation. * **D (Incorrect):** IL-1 (along with TNF) actually causes **increased** release of polymorphonuclear neutrophils (PMNs) from the bone marrow, leading to "leukocytosis" and a "left shift." **High-Yield NEET-PG Pearls:** * **The "Endogenous Pyrogens":** IL-1 and TNF are the chief mediators of fever. They act on the hypothalamus to increase prostaglandin ($PGE_2$) synthesis, raising the thermoregulatory set point. * **Acute Phase Response:** IL-1 stimulates the liver to produce acute-phase reactants (e.g., CRP, Fibrinogen). * **Dual Forms:** IL-1 exists as IL-1α (membrane-bound) and IL-1β (secreted). The activation of the **Inflammasome** (caspase-1) is required to cleave pro-IL-1β into its active secreted form [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 196, 204-206.

Q: Which arachidonic acid metabolite acts as a vasoconstrictor?

TXA2. Arachidonic acid (AA) metabolites, known as eicosanoids, are critical mediators of inflammation. They are synthesized via two major pathways: the **Cyclooxygenase (COX)** pathway (producing prostaglandins and thromboxanes) and the **Lipoxygenase (LOX)** pathway (producing leukotrienes and lipoxins) [1]. **Correct Option: A. TXA2 (Thromboxane A2)** TXA2 is synthesized primarily by platelets via the enzyme thromboxane synthase. Its primary physiological roles are **potent vasoconstriction** and the promotion of **platelet aggregation** [1]. This makes it a key mediator in the initial response to vascular injury (hemostasis). **Incorrect Options:** * **B. PGI2 (Prostacyclin):** Produced by vascular endothelium, it is the functional antagonist to TXA2. It causes **vasodilation** and **inhibits** platelet aggregation [1]. * **C. PGD2:** Primarily produced by mast cells; it causes **vasodilation** and increases vascular permeability [1]. * **D. PGE2:** A major mediator of inflammation that causes **vasodilation** [1]. It is also famously associated with inducing **pain** (sensitizing nociceptors) and **fever** (acting on the hypothalamus). **NEET-PG High-Yield Pearls:** * **Vasoconstrictors:** TXA2, Leukotrienes C4, D4, E4 [1]. * **Vasodilators:** PGI2, PGE1, PGE2, PGD2 [1]. * **Pain & Fever:** PGE2 is the key mediator [1]. * **Chemotaxis:** LTB4 is the most potent AA metabolite for neutrophil chemotaxis (Remember: "B4" for "Before" others arrive) [1]. * **Aspirin Mechanism:** Irreversibly inhibits COX-1 and COX-2, shifting the balance toward vasodilation and anti-aggregation by inhibiting TXA2 synthesis in platelets [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 95-96.

Q: The process by which leukocytes are arranged along the endothelium is called:

Margination. **Explanation:** In the early stages of acute inflammation, hemodynamic changes lead to a decrease in blood flow velocity (stasis). Normally, blood cells travel in the central axial column of the vessel. As stasis occurs, the smaller red blood cells aggregate into rouleaux, pushing the heavier leukocytes toward the periphery of the vessel lumen [1]. **1. Why Margination is Correct:** **Margination** is the specific process where leukocytes move out of the central axial stream and assume a peripheral position along the vascular endothelial surface [1]. This is the prerequisite step before any physical interaction (binding) with the endothelium occurs. **2. Analysis of Incorrect Options:** * **Rolling:** This is the next step after margination. Leukocytes tumble along the endothelial surface, mediated by transient, low-affinity interactions between **Selectins** (E, P, and L-selectins) and their carbohydrate ligands (Sialyl-Lewis X) [1]. * **Diapedesis (Transmigration):** This refers to the actual squeezing of leukocytes through the endothelial intercellular junctions to enter the extravascular space. It is primarily mediated by **PECAM-1 (CD31)**. * **Chemotaxis:** This is the process of unidirectional migration of leukocytes toward the site of injury along a chemical gradient (e.g., C5a, LTB4, IL-8, or bacterial products). **High-Yield Clinical Pearls for NEET-PG:** * **Adhesion** (firm binding) is mediated by **Integrins** (LFA-1, MAC-1) on leukocytes and **ICAM-1/VCAM-1** on the endothelium [1]. * **Leukocyte Adhesion Deficiency (LAD) Type 1** is caused by a defect in the **CD18** subunit of integrins, leading to impaired firm adhesion and recurrent infections without pus formation. * **LAD Type 2** is a defect in **Sialyl-Lewis X**, affecting the **Rolling** phase. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Migration in the tissues toward a chemotactic stimulus, pp. 86-87.

Question 1

What is the primary role of IL-1?

Accepted Answer

T lymphocyte activation

Answer

Delayed wound healing

Answer

Increased pain perception

Answer

Decreased PMN release from bone marrow

Question 2

A 5-year-old male presents with fever and cervical lymphadenopathy. Histopathological examination of the cervical lymph nodes shows what finding?

Accepted Answer

Caseating granuloma

Answer

Non-caseating granuloma

Answer

Stellate granuloma

Answer

Fat necrosis

Question 3

Fibrinoid necrosis is seen in all EXCEPT-

Accepted Answer

Sarcoidosis

Answer

Polyarteritis nodosa

Answer

Systemic Lupus Erythematosus

Answer

Hepatitis B Virus infection

Question 4

In an inflammatory response, which of the following are involved in the recognition of microbes or damaged cells?

Accepted Answer

All of the above

Answer

Toll-like receptors

Answer

NOD-Like receptors

Answer

Mannose-binding lectin protein

Question 5

All of the following facts related to chronic inflammation are true, except:

Accepted Answer

Dominant cells in chronic inflammation are neutrophils.

Answer

It can be severe and progressive.

Answer

Granulomas are an example of chronic inflammation.

Answer

Chronic inflammation is involved in the pathogenesis of metabolic syndrome and certain cancers.

Question 6

A 40-year-old man complains of a 2-week history of increasing abdominal pain and yellow discoloration of his sclera. Physical examination reveals right upper quadrant pain. Laboratory studies show elevated serum levels of alkaline phosphatase (520 U/dL) and bilirubin (3.0 mg/dL). A liver biopsy shows portal fibrosis, with scattered foreign bodies consistent with schistosome eggs. Which of the following inflammatory cells is most likely to predominate in the portal tracts in the liver of this patient?

Accepted Answer

Eosinophils

Answer

Basophils

Answer

Macrophages

Answer

Monocytes

Question 7

Which arachidonic acid metabolite acts as a vasoconstrictor?

Accepted Answer

TXA2

Answer

PGI2

Answer

PGD2

Answer

PGE2

Question 8

Growth stimulators and inhibitors are produced by which of the following cell types?

Accepted Answer

Eosinophils

Answer

Red blood cells

Answer

Macrophages

Answer

Platelets

Question 9

A 75-year-old woman presents with recent onset of chest pain, fever, and productive cough with rust-colored sputum. A chest X-ray reveals an infiltrate in the right middle lobe. Sputum cultures are positive for Streptococcus pneumoniae. Phagocytic cells in the patient's affected lung tissue generate bactericidal hypochlorous acid using which of the following enzymes?

Accepted Answer

Myeloperoxidase

Answer

Catalase

Answer

Cyclooxygenase

Answer

Superoxide dismutase

Question 10

The process by which leukocytes are arranged along the endothelium is called:

Accepted Answer

Margination

Answer

Rolling

Answer

Diapedesis

Answer

Chemotaxis

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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