Inflammation and Repair Practice Questions

Q: Which defect is identified by the nitroblue tetrazolium test?

Phagocytosis. The **Nitroblue Tetrazolium (NBT) test** is a classic diagnostic tool used to assess the **oxidative burst** capacity of phagocytes (neutrophils and macrophages). Phagocytosis involves the ingestion of pathogens, followed by their destruction via reactive oxygen species (ROS) [1]. This process is mediated by the **NADPH oxidase enzyme complex**. In a normal cell, NADPH oxidase reduces the yellow NBT dye into insoluble, dark blue **formazan crystals**. A positive NBT test (blue color) indicates intact phagocytic killing power. A negative NBT test (no color change) indicates a defect in the oxidative burst, most characteristically seen in **Chronic Granulomatous Disease (CGD)**. Complement defects are typically screened using the **CH50 assay** (for classical pathway) or **AH50** (for alternative pathway). T-cell function is evaluated via delayed-type hypersensitivity (DTH) skin tests, flow cytometry (CD3/CD4/CD8 counts), or mitogen stimulation assays. B-cell function is assessed by measuring serum immunoglobulin levels (IgG, IgA, IgM) or quantifying CD19/CD20+ cells via flow cytometry. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 89-92.

Q: Teuton giant cells are seen in which of the following conditions?

Xanthoma. **Explanation:** **Touton giant cells** (also known as xanthelasmic giant cells) are the hallmark histological feature of **Xanthomas**. These are specialized multinucleated giant cells formed by the fusion of macrophages (histiocytes). **Why Xanthoma is correct:** The underlying mechanism involves the accumulation of lipids [1]. In Touton giant cells, nuclei form a complete or partial ring around a central area of homogeneous eosinophilic cytoplasm. Crucially, the **peripheral cytoplasm** outside the ring of nuclei appears **foamy or vacuolated** due to the presence of processed lipids (cholesterol) [1]. This characteristic "wreath-like" arrangement is diagnostic of lesions with high lipid content, such as xanthomas, xanthogranulomas, and fat necrosis. **Why other options are incorrect:** * **Sarcoidosis:** Characterized by non-caseating granulomas containing **Langhans giant cells** and specific inclusions like **Asteroid bodies** and **Schaumann bodies**. * **Tuberculosis:** Features caseating granulomas with **Langhans giant cells**, where nuclei are arranged in a peripheral "horseshoe" pattern. * **Foreign body granuloma:** Contains **Foreign body giant cells**, where nuclei are disorganized and scattered randomly throughout the cytoplasm. **High-Yield Clinical Pearls for NEET-PG:** * **Touton Giant Cell:** Central eosinophilic cytoplasm + Ring of nuclei + Peripheral foamy cytoplasm. * **Langhans Giant Cell:** Peripheral horseshoe nuclei (seen in TB, Sarcoidosis). * **Foreign Body Giant Cell:** Haphazard/scattered nuclei. * **Aschoff Cells:** Found in Rheumatic Heart Disease (Anitschkow cells are the mononuclear precursors). * **Warthin-Finkeldey Cells:** Multinucleated giant cells seen in Measles. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Cellular Responses to Stress and Toxic Insults: Adaptation, Injury, and Death, pp. 73-74.

Q: Which of the following is a C-X-C chemokine?

IL-8. ### Explanation Chemokines are a family of small cytokines classified into four main groups based on the arrangement of the first two conserved **cysteine (C) residues** at the N-terminus. **1. Why IL-8 is the Correct Answer:** **IL-8 (Interleukin-8)**, also known as CXCL8, is the prototypical **C-X-C (alpha) chemokine**. In this group, the first two cysteine residues are separated by a single amino acid (X). IL-8 is primarily produced by macrophages and endothelial cells; its primary function is the **potent chemoattraction and activation of neutrophils** to sites of inflammation. **2. Analysis of Incorrect Options:** * **A. Fractalkine (CX3CL1):** This is the only member of the **C-X3-C (delta)** family. It has three amino acids separating the two cysteines. It is unique because it exists in both membrane-bound and soluble forms, acting as both an adhesion molecule and a chemoattractant. * **B. Lymphotactin (XCL1):** This belongs to the **C (gamma)** family. These chemokines lack the first and third of the four characteristic cysteines, possessing only one Cysteine residue. It is primarily chemotactic for T-cells. * **C. Rantes (CCL5):** This belongs to the **C-C (beta)** family, where the first two cysteines are adjacent. Other members include MCP-1 and MIP-1α. These generally attract monocytes, eosinophils, and lymphocytes, but *not* neutrophils. ### High-Yield Clinical Pearls for NEET-PG: * **Neutrophil Recruitment:** IL-8 is the "gold standard" marker for neutrophil chemotaxis. * **HIV Connection:** Chemokine receptors act as co-receptors for HIV entry: **CCR5** (for R5 tropic strains) and **CXCR4** (for X4 tropic strains). * **Mnemonic:** **C-C** chemokines (like Rantes) attract **C**ells other than neutrophils; **C-X-C** (like IL-8) attracts neutrophils.

Question 1

Which defect is identified by the nitroblue tetrazolium test?

Accepted Answer

Phagocytosis

Answer

Complement

Answer

T cell

Answer

B cell

Question 2

Increased capillary permeability is caused by all of the following except?

Accepted Answer

Renin

Answer

Anaphylatoxin

Answer

5-hydroxytryptamine

Answer

Histamine

Question 3

Bronchospasm is initiated by?

Accepted Answer

Leukotrienes

Answer

C5a

Answer

C3a

Answer

Acetylcholines

Question 4

All of the following are pyrogenic cytokines, except?

Accepted Answer

Interleukin 18 (IL-18)

Answer

Interleukin 6 (IL-6)

Answer

Tumor Necrosis Factor (TNF)

Answer

Interferon alpha (IFN-a)

Question 5

Teuton giant cells are seen in which of the following conditions?

Accepted Answer

Xanthoma

Answer

Sarcoidosis

Answer

Tuberculosis

Answer

Foreign body granuloma

Question 6

Non-caseating granuloma is characteristically seen in:

Accepted Answer

Sarcoidosis

Answer

Syphilis

Answer

Tuberculosis

Answer

Cat-scratch disease

Question 7

All of the following are characteristic of exudates EXCEPT:

Accepted Answer

Protein content less than 1 gm/dL

Answer

Predominantly polymorphonuclear cells

Answer

Specific gravity greater than 1.015

Answer

Turbid appearance of the fluid

Question 8

Which of the following is an endogenous chemoattractant?

Accepted Answer

C5a

Answer

Bacterial products

Answer

Lipopolysaccharide A

Answer

C8

Question 9

Which interleukin is primarily associated with fever and inflammation?

Accepted Answer

Interleukin 1

Answer

Interleukin 12

Answer

Interleukin 5

Answer

Interleukin 2

Question 10

Which of the following is a C-X-C chemokine?

Accepted Answer

IL-8

Answer

Fractalkine

Answer

Lymphotactin

Answer

Rantes

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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