Inflammation and Repair Practice Questions

Q: What is the PRIMARY mechanism by which Interleukin-1 (IL-1) induces fever?

Endogenous pyrogen. ***Endogenous pyrogen*** - **IL-1** is a potent **endogenous pyrogen** that acts directly on the **hypothalamus**, the body's thermoregulatory center. - It stimulates the production of **prostaglandin E2 (PGE2)** in the hypothalamus, which then resets the body's thermoregulatory set point to a higher temperature, leading to fever. *Stimulates antibody production* - While IL-1 can have broader immune functions and can influence B cell activity, its **primary role in fever** production is not through antibody stimulation. - Antibody production is a function of **B lymphocytes** and is primarily driven by antigen presentation and T cell help. *Inhibits inflammation* - **IL-1** is a key **pro-inflammatory cytokine** that promotes inflammation, rather than inhibiting it. - It induces the expression of various adhesion molecules and inflammatory mediators, contributing to the inflammatory response. *Activates complement cascade* - The **complement cascade** is a part of the innate immune system, typically activated by **antigen-antibody complexes** (classical pathway) or **microbial surfaces** (alternative and lectin pathways). - While IL-1 plays a role in overall immune responses, its direct mechanism for inducing fever does not primarily involve activating the complement system.

Q: Reactive nitrogen species for killing of microbes are mainly derived from

Nitric Oxide [NO]. ***Nitric Oxide [NO]*** - **Nitric oxide (NO)** is a key reactive nitrogen species produced by immune cells (e.g., macrophages) via nitric oxide synthase, which is crucial for killing intracellular pathogens. - It reacts with **superoxide radicals** to form other highly reactive and potent antimicrobial species like **peroxynitrite**. *Elemental nitrogen [N2]* - **Elemental nitrogen (N2)** is an inert gas constituting about 78% of the atmosphere and is not directly involved in the immune killing of microbes. - It must be "fixed" into biologically available forms by specific bacteria, a process distinct from host immune responses. *Nitrogen Dioxide [NO2]* - **Nitrogen dioxide (NO2)** can be formed from NO, particularly in the presence of oxygen, and can act as a reactive species, but **NO** is the primary precursor generated by immune cells for direct antimicrobial action. - While it has some oxidative potential, it is not the main biologically derived RNS for direct microbial control within phagocytes. *Nitrous Oxide [N2O]* - **Nitrous oxide (N2O)**, commonly known as laughing gas, is primarily used as an anesthetic agent and is not a significant **reactive nitrogen species** (RNS) involved in the host immune defense against microbes. - It is metabolically stable and does not participate in the cytotoxic reactions against pathogens like NO.

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: Lymphotactin is which type of chemokine?

C. ***C*** - **Lymphotactin**, also known as **XCL1**, is a chemokine belonging to the C chemokine subfamily. - This subfamily is characterized by having **only one cysteine residue** at the N-terminus, distinguishing it from other chemokine subfamilies. *CC* - **CC chemokines** (or β-chemokines) have **two adjacent cysteine residues** at their N-terminus. - Examples include **MCP-1** and **MIP-1α**, which primarily attract monocytes and macrophages. *CX3C* - **CX3C chemokines** possess a unique motif with **three amino acids separating the first two cysteine residues** (C-X3-C). - **Fractalkine (CX3CL1)** is the sole member of this subfamily, acting as both an adhesion molecule and a chemoattractant. *CXC* - **CXC chemokines** (or α-chemokines) have **one amino acid separating the first two cysteine residues** at their N-terminus (C-X-C). - Examples include **IL-8** and **IP-10**, which primarily attract neutrophils and lymphocytes, respectively.

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.

Question 1

What is the PRIMARY mechanism by which Interleukin-1 (IL-1) induces fever?

Accepted Answer

Endogenous pyrogen

Answer

Stimulates antibody production

Answer

Inhibits inflammation

Answer

Activates complement cascade

Question 2

Which of the following statements is MOST accurate regarding keloids?

Accepted Answer

It is associated with elevated growth factors

Answer

It does not extend beyond the wound

Answer

It does not recur after simple excision

Answer

None of the options

Question 3

Reactive nitrogen species for killing of microbes are mainly derived from

Accepted Answer

Nitric Oxide [NO]

Answer

Elemental nitrogen [N2]

Answer

Nitrogen Dioxide [NO2]

Answer

Nitrous Oxide [N2O]

Question 4

Which enzyme secreted by neutrophils catalyzes the production of hypochlorous acid for pathogen killing?

Accepted Answer

An enzyme that catalyzes the production of hypochlorous acid

Answer

A protein involved in immune response

Answer

An enzyme that breaks down proteins

Answer

A type of carbohydrate

Question 5

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 6

Primary granules contain which enzyme?

Accepted Answer

Myeloperoxidase (MPO)

Answer

Hydrolases

Answer

Lactoferrin

Answer

Phospholipase A2

Question 7

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 8

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

Accepted Answer

P-selectin

Answer

ICAM-1

Answer

VCAM-1

Answer

CD31

Question 9

Lymphotactin is which type of chemokine?

Accepted Answer

C

Answer

CC

Answer

CX3C

Answer

CXC

Question 10

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

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

On this page

Practice by Chapter

Want unlimited practice?