Inflammation and Repair Practice Questions

Q: What best describes Neutrophil Extracellular Traps (NETs)?

All of the above. **Explanation:** Neutrophil Extracellular Traps (NETs) represent a specialized form of innate immune defense where neutrophils "sacrifice" themselves to trap and kill pathogens. * **Option A is correct:** NETs are **extracellular fibrillar networks** composed of a meshwork of nuclear chromatin (DNA and histones). This sticky scaffold physically traps bacteria, fungi, and parasites, preventing their systemic spread. * **Option B is correct:** During the process of **NETosis**, granule proteins (such as myeloperoxidase, elastase, and cathepsin G) are released and bound to the chromatin fibers [1]. This creates a **high local concentration of antimicrobial substances**, allowing for efficient killing of pathogens without relying solely on phagocytosis. * **Option C is correct:** NETs are produced in response to various **inflammatory mediators**, including infectious pathogens (bacteria, fungi), cytokines (IL-8), and chemokines. Since all individual statements accurately describe the structure, function, and induction of NETs, **Option D is the correct answer.** **High-Yield NEET-PG Pearls:** 1. **NETosis:** This is a distinct form of programmed cell death (different from apoptosis and necrosis) where the neutrophil membrane ruptures to release its contents. 2. **Clinical Correlation:** NETs have a "double-edged sword" nature. While they fight infection, they are implicated in **autoimmune diseases** (e.g., SLE, where NET DNA may act as an autoantigen) and **thrombosis** (providing a scaffold for platelet aggregation) [1]. 3. **Key Enzyme:** **PAD4** (Peptidylarginine deiminase 4) is essential for NET formation as it causes histone citrullination, leading to chromatin decondensation. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 91-93.

Q: Which of the following composes the majority of the leukocyte infiltrate after the first 24 hours of an inflammatory response?

Monocyte. In acute inflammation, the cellular infiltrate follows a predictable chronological sequence determined by the expression of adhesion molecules and the lifespan of specific leukocytes [1]. **Why Monocytes are the correct answer:** During the first **6 to 24 hours**, neutrophils predominate because they are more numerous in the blood, respond more rapidly to chemokines, and attach more firmly to adhesion molecules like P-selectin and E-selectin [1]. However, neutrophils are short-lived and undergo apoptosis within 24–48 hours. After the initial **24 to 48 hours**, **monocytes** (which become macrophages in tissue) replace them [1]. Monocytes survive longer, can proliferate in the tissues, and are better equipped for the sustained phagocytosis and repair required in the later stages of inflammation. **Analysis of Incorrect Options:** * **A. Neutrophils:** These are the "first responders" and dominate the infiltrate only during the first 6–24 hours [1]. * **C. Lymphocytes:** These are typically associated with chronic inflammation or specific viral infections (e.g., viral meningitis), rather than the immediate post-24-hour window of a standard acute response. * **D. Eosinophils:** These are the predominant cells in hypersensitivity reactions (Type I) and parasitic infections, but not in general acute inflammation. **High-Yield NEET-PG Pearls:** * **Exceptions to the Rule:** In **Pseudomonas** infections, neutrophils persist for several days. In **viral infections**, lymphocytes may be the first cells to arrive. In **hypersensitivity reactions**, eosinophils may dominate early. * **Key Mediator:** Monocyte recruitment is largely driven by MCP-1 (Monocyte Chemoattractant Protein-1). * **Sequence:** Neutrophils (6–24 hrs) $\rightarrow$ Monocytes/Macrophages (24–48 hrs) [1]. **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

An 87-year-old woman has had a cough productive of yellowish sputum for the past 2 days. On examination her temperature is 37°C. A chest radiograph shows bilateral patchy infiltrates. Her peripheral blood shows leukocytosis. A week later she is afebrile. Which of the following is the most likely outcome of her pulmonary disease?

Accepted Answer

Resolution

Answer

Chronic inflammation

Answer

Fibrous scarring

Answer

Neoplasia

Question 2

Exudation of plasma and leukocytes in acute inflammation is primarily from which of the following vascular structures?

Accepted Answer

Venules

Answer

Capillaries

Answer

Arterioles

Answer

Arterioles and capillaries

Question 3

What best describes Neutrophil Extracellular Traps (NETs)?

Accepted Answer

All of the above

Answer

NETs are extracellular fibrillar networks.

Answer

NETs provide a high concentration of antimicrobial substances at sites of infection.

Answer

NETs are produced by neutrophils in response to inflammatory mediators.

Question 4

Which of the following is not a pyrogenic cytokine?

Accepted Answer

IL-18

Answer

IL-1

Answer

TNF

Answer

IFN-a

Question 5

Which of the following are acute phase reactants in acute inflammation?

Accepted Answer

Haptoglobin

Answer

Albumin

Answer

Fibrinogen

Answer

Gammaglobulin

Question 6

Which of the following composes the majority of the leukocyte infiltrate after the first 24 hours of an inflammatory response?

Accepted Answer

Monocyte

Answer

Neutrophil

Answer

Lymphocyte

Answer

Eosinophil

Question 7

Increased accumulation of fluid in the interstitial space is described as?

Accepted Answer

Edema

Answer

Effusion

Answer

Transudate

Answer

Exudate

Question 8

In muscle hypertrophy, which myosin isoform changes?

Accepted Answer

Alpha

Answer

Beta

Answer

Theta

Answer

Delta

Question 9

Which is considered the most important pyogenic Interleukin?

Accepted Answer

IL-1

Answer

IL-2

Answer

IL-6

Answer

IL-8

Question 10

Bronchospasm is initiated by?

Accepted Answer

Leukotrienes

Answer

C5a

Answer

C3a

Answer

Acetylcholines

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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