Inflammation and Repair Practice Questions

Q: Which one of the following statements is false regarding chronic granulomatous disease?

It is an autosomal dominant disease. ### It is an autosomal dominant disease - The most common and severe form of chronic granulomatous disease (CGD) is inherited as an **X-linked recessive disorder**. - There are also autosomal recessive forms, but **never autosomal dominant inheritance**. *Recurrent staphylococcal infections are usual in this disease* - Patients with CGD are particularly susceptible to infections with **catalase-positive organisms** like *Staphylococcus aureus* because their phagocytes cannot effectively kill these microbes. - This is due to a defect in the **NADPH oxidase enzyme**, which impairs the production of reactive oxygen species essential for bacterial killing [1]. *Nitro blue tetrazolium test is useful for screening* - The **nitroblue tetrazolium (NBT) test** is a traditional screening method for CGD, as it detects the ability of phagocytes to produce a **respiratory burst** and reduce NBT dye [1]. - In CGD, the NBT dye remains yellow (unreduced) due to the absence or deficiency of NADPH oxidase activity. *It is characterized by abnormal bacterial phagocytosis* - CGD is characterized by **defective intracellular killing of phagocytosed bacteria and fungi**, not abnormal phagocytosis itself. - Phagocytes (neutrophils, macrophages) can engulf microbes normally, but they fail to produce the **oxidative burst** necessary to destroy them [1].

Q: Regeneration is characterized by:

Repairing by same type of tissue. ***Repairing by same type of tissue*** - **Regeneration** involves the replacement of damaged cells and tissues with cells of the **same type**, leading to a complete restoration of normal structure and function [1]. - This process is seen in tissues with high proliferative capacity, like the **epidermis** or the **liver**, following injury [2]. *Granulation tissue* - **Granulation tissue** is characteristic of **repair by fibrosis** (scar formation), not regeneration [1]. - It consists of proliferating fibroblasts, new blood vessels (angiogenesis), and inflammatory cells, which eventually mature into a fibrous scar. *Repairing by different type of tissue* - The replacement of damaged tissue with a **different type of tissue** (typically fibrous connective tissue) is known as **repair by fibrosis** or **scar formation** [1]. - This occurs when the tissue's regenerative capacity is limited or when the injury is severe, resulting in the loss of normal tissue architecture and function [3]. *Cellular proliferation is largely regulated by biochemical factors* - While **cellular proliferation** is indeed regulated by **biochemical factors** (growth factors, cytokines) in both regeneration and repair, this statement describes a mechanism common to cellular growth and healing in general, not a defining characteristic unique to regeneration [1]. - This regulation guides both the replacement with original tissue (regeneration) and scar formation, so it's not specific enough to define regeneration alone. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 113-115. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 112-113. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 113.

Q: Which of the following requires calcium for ligand binding?

P-selectin. ***P-selectin*** - **P-selectin** is a **C-type (calcium-dependent) lectin** that requires **Ca²⁺ ions** for its carbohydrate recognition domain to function. - The calcium is essential for maintaining the proper **conformational structure** of the lectin domain, enabling it to bind carbohydrate ligands like **sialyl-Lewis X** on leukocytes. - Expressed on activated endothelial cells and platelets during inflammation. *Sialyl-Lewis X* - This is a **carbohydrate ligand** (not a receptor) found on leukocytes that binds to selectins. - It does not itself require calcium for binding; rather, it is recognized by calcium-dependent selectins. *LFA-1* - **LFA-1** is an **integrin** that binds to ICAMs. - While integrins require **Mg²⁺** (not Ca²⁺) for optimal binding, LFA-1 is not primarily characterized as calcium-dependent for ligand binding. *PSGL-1* - **PSGL-1** is a **glycoprotein ligand** on leukocytes, not a receptor. - It does not require calcium for its own function; the calcium dependency is on the selectin side of the interaction.

Q: Which of the following helps in movement and adhesion?

CD31. ***CD31*** - **CD31 (Platelet Endothelial Cell Adhesion Molecule-1, PECAM-1)** plays a critical role in **leukocyte transendothelial migration**, which is essential for leukocyte movement and adherence to endothelial cells during inflammation. - It mediates both **homophilic and heterophilic binding** at intercellular junctions, facilitating the passage of leukocytes through vessel walls. *PGE2* - **Prostaglandin E2 (PGE2)** is involved in inflammation, primarily causing **vasodilation**, fever, and pain sensitization. - While it modulates immune responses, its primary function is not direct cell movement or adhesion. *MCP1* - **MCP-1 (Monocyte Chemoattractant Protein-1), also known as CCL2**, is a chemokine that primarily functions in **chemoattraction** of monocytes, macrophages, and T cells. - It guides these cells to sites of inflammation but does not directly mediate adhesion to endothelial surfaces. *LTB4* - **Leukotriene B4 (LTB4)** is a potent **chemoattractant for neutrophils**, guiding their migration to inflammatory sites. - Its main function is **chemotaxis**, promoting the directed movement of neutrophils, rather than direct cell adhesion.

Q: Granulomas in lymph nodes are seen in all of the following infections EXCEPT:

Staph Aureus. ***Staph Aureus*** - *Staphylococcus aureus* typically causes **suppurative (pus-forming)** infections leading to **abscesses** and **pyogenic inflammation**, not granulomas [2], [3]. - Lymph node involvement with *S. aureus* usually manifests as **acute lymphadenitis** with neutrophil infiltration, not organized granulomatous structures [2]. *Histoplasmosis* - **Histoplasmosis**, caused by *Histoplasma capsulatum*, is a fungal infection that commonly forms **granulomas** in affected tissues, including lymph nodes [1]. - These granulomas often resemble those seen in tuberculosis and can be **caseating or non-caseating** [1]. *Brucellosis* - **Brucellosis**, caused by *Brucella* species, is a zoonotic bacterial infection that classically forms **non-caseating granulomas** in multiple organs including lymph nodes, liver, and spleen. - The granulomas are characterized by epithelioid histiocytes and may contain multinucleated giant cells. *TB* - **Tuberculosis (TB)**, caused by *Mycobacterium tuberculosis*, is the classic example of an infection that forms **caseating granulomas** in affected lymph nodes [3]. - These granulomas are characterized by **central caseous necrosis** surrounded by epithelioid histiocytes, lymphocytes, and Langhans giant cells [4]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 717. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, pp. 592-593. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, p. 360. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 379-380.

Q: Which of the following complement components acts as a chemoattractant?

C5a. ***Correct: C5a*** - **C5a** is a powerful **chemoattractant** for neutrophils, monocytes, and macrophages, guiding them to sites of infection and inflammation. - It also acts as an **anaphylatoxin**, promoting inflammation through mast cell degranulation and histamine release. *Incorrect: C3b* - The primary function of **C3b** is **opsonization**, marking pathogens for phagocytosis by immune cells. - It also plays a crucial role in forming the **C5 convertase** in the complement activation pathways. *Incorrect: C4a* - **C4a** is a weak **anaphylatoxin** involved in modulating inflammation, but its chemotactic activity is minimal. - It is generated during the activation of the **classical** and **lectin pathways** of complement. *Incorrect: C3a* - **C3a** is an **anaphylatoxin** that promotes inflammation by inducing degranulation of mast cells and basophils. - It has some weak chemotactic properties but is considerably less potent than **C5a** in attracting immune cells.

Q: Most effective bactericidal system within phagocytes is-

Reactive oxygen metabolite mediated. ***Reactive oxygen metabolite mediated*** - The production of **reactive oxygen metabolites** (like superoxide, hydrogen peroxide, and hydroxyl radicals) through the **respiratory burst** is a highly potent mechanism for killing phagocytosed bacteria. - These highly reactive molecules cause **oxidative damage** to bacterial components, leading to their degradation and death. *Cationic basic protein mediated* - **Cationic proteins** (e.g., defensins) have antimicrobial properties by damaging bacterial membranes, but they are generally less potent than reactive oxygen species in overall bacterial killing within phagocytes. - While important, they contribute to a broader array of antimicrobial mechanisms but are not considered the *most effective* single system. *Lysozyme mediated* - **Lysozyme** primarily targets bacterial **peptidoglycan**, breaking down bacterial cell walls, especially in gram-positive bacteria. - It is an important antimicrobial enzyme, but its effectiveness is limited against many gram-negative bacteria with outer membranes and it is generally less destructive than the radical-forming reactive oxygen species. *Lactoferrin mediated* - **Lactoferrin** primarily acts by **chelating iron**, which is an essential nutrient for bacterial growth, thereby inhibiting bacterial proliferation. - While important for bacteriostasis, its direct bactericidal activity is often limited compared to the direct damaging effects of reactive oxygen species.

Question 1

Which one of the following statements is false regarding chronic granulomatous disease?

Accepted Answer

It is an autosomal dominant disease

Answer

Recurrent staphylococcal infections are usual in this disease

Answer

Nitro blue tetrazolium test is useful for screening

Answer

It is characterized by abnormal bacterial phagocytosis

Question 2

Regeneration is characterized by:

Accepted Answer

Repairing by same type of tissue

Answer

Granulation tissue

Answer

Repairing by different type of tissue

Answer

Cellular proliferation is largely regulated by biochemical factors

Question 3

Which of the following requires calcium for ligand binding?

Accepted Answer

P-selectin

Answer

Sialyl-Lewis X

Answer

LFA-1

Answer

PSGL-1

Question 4

Which of the following helps in movement and adhesion?

Accepted Answer

CD31

Answer

PGE2

Answer

MCP1

Answer

LTB4

Question 5

Granulomas in lymph nodes are seen in all of the following infections EXCEPT:

Accepted Answer

Staph Aureus

Answer

Histoplasmosis

Answer

Brucellosis

Answer

TB

Question 6

Which of the following complement components acts as a chemoattractant?

Accepted Answer

C5a

Answer

C3b

Answer

C4a

Answer

C3a

Question 7

Fibroblasts in healing wound are derived from -

Accepted Answer

Local mesenchyme

Answer

Epithelium

Answer

Endothelium

Answer

Bone marrow

Question 8

Liver after transplant enlarges by -

Accepted Answer

Both

Answer

Increase in number of cells

Answer

Increase in size of cell

Answer

None of the options

Question 9

Most effective bactericidal system within phagocytes is-

Accepted Answer

Reactive oxygen metabolite mediated

Answer

Cationic basic protein mediated

Answer

Lysozyme mediated

Answer

Lactoferrin mediated

Question 10

Asteroid bodies in non-caseating granulomas are characteristically seen in:

Accepted Answer

Sarcoidosis

Answer

Sporotrichosis

Answer

Chromoblastomycosis

Answer

Syphilis

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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