Inflammation and Repair Practice Questions

Q: All of the following cell types undergo cell division, EXCEPT:

Cardiac muscle cell. ***Cardiac muscle cell*** - **Cardiac muscle cells** are terminally differentiated and largely lose their ability to divide shortly after birth. - While some limited regenerative capacity exists, they do not undergo significant cell division for repair or growth in the adult heart. *Pericyte* - **Pericytes** are multipotent cells associated with capillaries and postcapillary venules and are involved in angiogenesis and tissue repair. - They can differentiate into **fibroblasts, smooth muscle cells, osteoblasts, and adipocytes**, and their proliferative capacity is crucial for these functions, especially after injury. *Smooth muscle cell* - **Smooth muscle cells** retain their ability to divide throughout life and can proliferate in response to injury or hormonal stimuli. - This proliferative capacity is important for the growth and repair of organs like the uterus and blood vessels, and can contribute to conditions like **atherosclerosis**. *Satellite cell of skeletal muscle* - **Satellite cells** are quiescent muscle stem cells located between the basal lamina and sarcolemma of muscle fibers. - Upon muscle injury, they become activated, proliferate, and differentiate into new muscle fibers, playing a critical role in **skeletal muscle regeneration** and repair.

Q: What is responsible for regeneration of liver cells?

HGF. **HGF** - **Hepatocyte growth factor (HGF)** is the primary growth factor responsible for stimulating hepatocyte proliferation and migration, playing a crucial role in **liver regeneration** after injury or resection. - It acts as a potent **mitogen** for hepatocytes, promoting their entry into the cell cycle and division. *VEGF* - **Vascular endothelial growth factor (VEGF)** is primarily involved in **angiogenesis**, the formation of new blood vessels. - While important for tissue repair, it does not directly stimulate the proliferation of liver cells themselves. *TGF-beta* - **Transforming growth factor-beta (TGF-β)** is generally considered an **inhibitor of cell proliferation** and a promoter of fibrosis in the liver. - It can suppress hepatocyte growth and promote the differentiation of stellate cells into myofibroblasts, leading to **scar formation**. *IFN-γ* - **Interferon-gamma (IFN-γ)** is a cytokine primarily involved in **immune responses** and has anti-proliferative and pro-apoptotic effects on various cell types. - It does not promote liver cell regeneration; instead, it can be involved in liver injury and fibrosis during chronic inflammation.

Q: Nuclei are arranged at the cell periphery in which type of cell?

Langhans giant cells. ***Langhans giant cells*** - These are **multinucleated giant cells** formed by the fusion of multiple epithelioid macrophages. - Their nuclei typically form a **horseshoe or ring-like arrangement** at the periphery of the cell cytoplasm. *Merkel cells in the skin* - Merkel cells are **neuroendocrine cells** found in the basal layer of the epidermis. - They possess a **single, irregularly lobed nucleus** and are associated with touch sensation, not multiple peripheral nuclei. *Natural Killer (NK) cells* - NK cells are **lymphocytes** characterized by a **single, round nucleus** and granular cytoplasm. - Their primary function is to kill infected or cancerous cells, and their nuclear arrangement is not peripheral. *Neutrophils in the immune response* - Neutrophils are **polymorphonuclear leukocytes** with a characteristic **multi-lobed nucleus**. - While the nucleus is segmented, it is not arranged peripherally in a ring, but rather centrally within the cell.

Q: What is the primary function of the peroxidase enzyme found in neutrophils?

Microbial killing. ***Microbial killing*** - **Myeloperoxidase (MPO)**, found in neutrophil azurophilic granules, catalyzes the formation of **hypochlorous acid (HOCl)** from hydrogen peroxide (H2O2) and chloride ions (Cl-). - **HOCl** is a potent oxidant that effectively destroys ingested microbes within the phagolysosome. *Macrophage activation* - While neutrophils interact with macrophages, the primary function of their peroxidase enzyme is not to activate macrophages. - Macrophage activation is typically driven by cytokines and recognition of pathogen-associated molecular patterns (PAMPs). *Chemotactic agent* - Peroxidase itself is not a primary chemotactic agent that attracts other immune cells. - Chemotaxis is mainly mediated by chemokines and complement components. *Vasodilatation* - Vasodilatation is primarily controlled by mediators like **histamine**, **nitric oxide**, and **prostaglandins**, which are not directly produced by the peroxidase action. - Peroxidase's role is specifically within the neutrophil for microbial destruction.

Q: Which endothelial molecule is primarily involved in the rolling of leukocytes?

P-selectin. ***CD 34*** - CD 34 is a key **endothelial molecule** that facilitates leukocyte **rolling** during the initial stages of inflammation [1]. - It acts as a cell adhesion **molecule**, allowing immune cells to transiently adhere and roll along the vascular endothelium [1][2]. *VCAM 1* - VCAM 1 is mainly involved in the **adherence** and **firm adhesion** of leukocytes, rather than rolling [1][2]. - It primarily binds to **VLA-4** on activated lymphocytes, a step that occurs after rolling [2]. *CD 31* - CD 31 (also known as **PECAM-1**) plays a role in **transmigration** of leukocytes through the endothelium, not in rolling [3]. - Its primary function is in cell-to-cell interactions and **diapedesis** rather than initial adhesion [3]. *ICAM 1* - ICAM 1 is important for **firm attachment** and is involved later in the process after rolling [1][2]. - It interacts with the integrin **LFA-1** on leukocytes, which aids in strong adhesion following rolling [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 87. [2] 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. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 87-89.

Q: Leukocyte adhesion to endothelium is mediated by all except?

VCAM-4. ***VCAM 4*** - **VCAM-4** is not a recognized mediator for leukocyte adhesion; instead, **VCAM-1** plays a significant role in this process. - Adhesion is primarily mediated by interactions between leukocyte integrins and endothelial **selectins** and **VCAM-1** [1]. *E selectin* - **E selectin** is involved in the adhesion of leukocytes to endothelium, particularly during inflammation [1]. - It helps in the adhesion process during the **rolling** phase of leukocyte extravasation [2]. *L selectin* - **L selectin** is crucial for the initial adhesion of leukocytes to the **high endothelial venules** in lymphoid tissues [1]. - It facilitates leukocyte **homing** to lymphoid organs, aiding in a variety of immune responses. *VCAM 1* - **VCAM-1** is a key adhesion molecule that facilitates the binding of leukocytes to endothelial cells, particularly in inflammation [3]. - Interacts with the integrin **VLA-4** on leukocytes, promoting firm adhesion during the immune response. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 87. [2] 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. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 87-89.

Q: All of the following statements are true regarding neutrophil extracellular trapping (NET) except for which of the following?

NETs consist exclusively of mitochondrial DNA. ***NETs consist exclusively of mitochondrial DNA*** - NETs (Neutrophil Extracellular Traps) are made primarily of **nuclear chromatin**, not exclusively of mitochondrial DNA [2]. - While mitochondrial-DNA-containing extracellular traps have also been described in some forms of NET release, the primary and predominant component of NETs is **nuclear genetic material**, making the claim that they consist exclusively of mitochondrial DNA false. *It is detected in blood during sepsis* - NETs can indeed be found in the **circulation during sepsis**, serving as a defense mechanism against infections. - Their presence in blood indicates an **active immune response**, particularly in severe systemic infections. *It is produced in response to bacterial infection* - NET formation is a known response to **bacterial infections**, as neutrophils deploy them to capture and neutralize pathogens. - This process helps in controlling infections, showcasing the importance of NETs in **innate immunity**. *It is chromatin with antibacterial enzymes* - NETs consist primarily of **decondensed chromatin**, embedded with **antimicrobial proteins** and enzymes to combat pathogens [1][2]. - This characteristic underscores their role in targeting and eliminating invading microorganisms effectively. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 91-92. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 92-93.

Q: A 33-year-old man presents with a 5-week history of calf pain, swelling, and low-grade fever. Serum levels of creatinine kinase are elevated. A muscle biopsy reveals numerous eosinophils and he also has peripheral blood eosinophilia. Which of the following interleukins is primarily responsible for the increase in eosinophils in this patient?

IL-5. ***IL-5*** - **Interleukin-5 (IL-5)** is the **most potent and direct cytokine** responsible for the **differentiation, maturation, activation, and survival of eosinophils**. - IL-5 is produced primarily by **Th2 cells**, mast cells, and eosinophils themselves, and acts directly on eosinophil progenitors in the bone marrow. - In this patient with eosinophilic myositis (likely parasitic infection such as trichinosis), **IL-5 is the primary mediator** of the peripheral blood eosinophilia and tissue eosinophil infiltration. - **Clinical correlation:** Anti-IL-5 therapies (mepolizumab, reslizumab) are used to treat hypereosinophilic conditions, confirming IL-5's central role. *IL-4* - **Interleukin-4 (IL-4)** is produced by Th2 cells and mast cells and promotes the **differentiation of naive T cells into Th2 cells**. - While IL-4 initiates the Th2 immune response that eventually leads to IL-5 production, it does **not directly stimulate eosinophil production or recruitment**. - IL-4 is more involved in IgE class switching and allergic inflammation rather than direct eosinophil regulation. *IL-6* - **Interleukin-6 (IL-6)** is a pleiotropic cytokine involved in the **acute phase response**, inflammation, and hematopoiesis. - While it has broad effects on immune cells, it is **not primarily responsible** for eosinophil production or recruitment. - Elevated in many inflammatory conditions but not specific for eosinophilia. *IL-2* - **Interleukin-2 (IL-2)** is primarily involved in the **proliferation and differentiation of T lymphocytes** and activation of natural killer (NK) cells. - It plays no significant direct role in eosinophil production or recruitment. - More important for T cell-mediated immunity rather than eosinophilic responses.

Question 1

Primary granules contain which enzyme?

Accepted Answer

Myeloperoxidase (MPO)

Answer

Hydrolases

Answer

Lactoferrin

Answer

Phospholipase A2

Question 2

All of the following cell types undergo cell division, EXCEPT:

Accepted Answer

Cardiac muscle cell

Answer

Pericyte

Answer

Smooth muscle cell

Answer

Satellite cell of skeletal muscle

Question 3

What is responsible for regeneration of liver cells?

Accepted Answer

HGF

Answer

TGF-beta

Answer

VEGF

Answer

IFN-γ

Question 4

Nuclei are arranged at the cell periphery in which type of cell?

Accepted Answer

Langhans giant cells

Answer

Merkel cells in the skin

Answer

Natural Killer (NK) cells

Answer

Neutrophils in the immune response

Question 5

What is the primary function of the peroxidase enzyme found in neutrophils?

Accepted Answer

Microbial killing

Answer

Macrophage activation

Answer

Chemotactic agent

Answer

Vasodilatation

Question 6

Which endothelial molecule is primarily involved in the rolling of leukocytes?

Accepted Answer

P-selectin

Answer

ICAM-1

Answer

VCAM-1

Answer

CD31

Question 7

What is the definition of exudate?

Accepted Answer

Extravascular fluid that has a high protein concentration and contains cellular debris

Answer

Extravascular fluid that has a low protein concentration

Answer

Extravascular fluid with high glucose concentration

Answer

Extravascular fluid with low glucose concentration

Question 8

Leukocyte adhesion to endothelium is mediated by all except?

Accepted Answer

VCAM-4

Answer

L-selectin

Answer

VCAM-1

Answer

E-selectin

Question 9

All of the following statements are true regarding neutrophil extracellular trapping (NET) except for which of the following?

Accepted Answer

NETs consist exclusively of mitochondrial DNA

Answer

It is detected in blood during sepsis

Answer

It is chromatin with antibacterial enzymes

Answer

It is produced in response to bacterial infection

Question 10

A 33-year-old man presents with a 5-week history of calf pain, swelling, and low-grade fever. Serum levels of creatinine kinase are elevated. A muscle biopsy reveals numerous eosinophils and he also has peripheral blood eosinophilia. Which of the following interleukins is primarily responsible for the increase in eosinophils in this patient?

Accepted Answer

IL-5

Answer

IL-4

Answer

IL-6

Answer

IL-2

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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