Inflammation and Repair Practice Questions

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.

Q: What is one of the primary functions of Interleukin-1 (IL-1)?

Acts as an endogenous pyrogen. ***Acts as an endogenous pyrogen*** - **Interleukin-1 (IL-1)** is a key **pro-inflammatory cytokine** that plays a central role in the body's response to infection and injury. - One of its primary functions is to act as an **endogenous pyrogen**, meaning it can induce **fever** by promoting prostaglandin synthesis in the hypothalamus, thereby raising the body's set point temperature. *Inhibits T cell proliferation* - IL-1 generally **enhances T cell activation and proliferation**, particularly in conjunction with other signals, rather than inhibiting it. - **Immunosuppressive cytokines** like **TGF-β** or **IL-10** are known to inhibit T cell proliferation. *Suppresses antibody production* - IL-1 is generally involved in **promoting B cell activation** and **antibody production**, either directly or indirectly through its effects on T helper cells. - Cytokines like **IL-10** can sometimes suppress certain aspects of antibody production but IL-1 is not known for this role. *Reduces inflammatory cell recruitment* - IL-1 is a potent **pro-inflammatory cytokine** that actively **promotes the recruitment** of immune cells, such as neutrophils and monocytes, to sites of inflammation. - It does this by inducing the expression of **adhesion molecules** and **chemokines** on endothelial cells.

Q: First mediator of inflammation to be released is

Histamine. ***Histamine*** - Histamine is the **first mediator of inflammation released** by mast cells and basophils during an allergic or inflammatory response [1][3]. - It promotes **vasodilation** and increased vascular permeability, leading to typical symptoms of inflammation [1][2]. *PAF* - Platelet-activating factor (PAF) is released later in the inflammatory process and is primarily involved in **amplifying** the response rather than initiating it. - It plays a role in **platelet aggregation** and acting on vascular smooth muscle but is not the first released mediator. *Nitric oxide* - Nitric oxide is produced by endothelial cells and plays a role in **vascular relaxation and inflammation**, but it is not among the first mediators released. - It is involved in more **regulatory functions** in the inflammatory response rather than the initial trigger. *IL-1* - Interleukin-1 (IL-1) is a cytokine that is important for the **inflammatory response**, but it is produced after the initial release of mediators like histamine [2]. - It is primarily secreted by **activated macrophages** and contributes to the **amplification** of the immune response [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 84-85. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 101. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 93-94.

Q: Rolling of leucocytes on endothelial cells is mediated by which of the following?

P-selectin. ***P- selectin*** - P-selectin is a **cell adhesion molecule** crucial for the **rolling** of leukocytes on endothelial cells during the inflammatory response [1]. - It is expressed on activated endothelial cells and binds to **sialylated carbohydrates** on leukocytes, facilitating their transient adhesion [1]. *IL-8* - IL-8 is a **chemokine** that primarily acts as a chemotactic factor for neutrophils rather than mediating rolling on endothelium. - While it attracts leukocytes to sites of inflammation, it does not play a role in the initial contact or rolling process. *ICAM-1* - ICAM-1 is an **intercellular adhesion molecule** that facilitates **firm adhesion** rather than rolling of leukocytes. - It primarily interacts with **integrins** on leukocytes to stabilize their adhesion after rolling has occurred. *(3, integrin* - Integrins play a significant role in **firm adhesion** and not the rolling phase, interacting with receptors like ICAM-1. - The binding of integrins to their ligands occurs after leukocytes have initially rolled on the endothelium. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 87.

Q: Which of the following is derived from fibroblast cells?

Collagen. ***Collagen*** - Collagen is a structural protein that is predominantly produced by **fibroblast cells** in the extracellular matrix [1][2]. - It provides tensile strength and structural support to various tissues, playing a crucial role in wound healing and tissue repair [2]. *TGF-13* - Transforming Growth Factor-beta 1 (TGF-β1) is primarily produced by **immune cells** and is involved in cell growth and differentiation, not primarily by fibroblasts. - It plays a role in **fibrosis** and inflammation, but is not directly synthesized by fibroblast cells themselves. *MMP2* - Matrix Metalloproteinase-2 (MMP-2) is produced by various cell types, including **endothelial and epithelial cells**, but not predominantly by fibroblasts. - It is involved in the degradation of **extracellular matrix** components rather than being a product of fibroblast synthesis. *Angiopoietin* - Angiopoietin is primarily secreted by **endothelial cells** and plays a significant role in blood vessel formation and maturation. - It is not derived from fibroblast cells and is unrelated to their primary function of producing the extracellular matrix. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. With Illustrations By, pp. 31-32. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. With Illustrations By, pp. 34-35.

Q: Chemotaxis is mediated by-

Leukotriene B4 and C5a. ***Leukotriene B4 and C5a*** - Both **Leukotriene B4** [2] and **C5a** [1] are potent **chemoattractants** that guide the migration of neutrophils and other immune cells to sites of inflammation. - They are crucial in amplifying the **immune response**, particularly during acute inflammatory reactions. *Histamine* - Primarily involved in **vasodilation** and increased **vascular permeability**, rather than mediating chemotaxis. - Does not specifically attract immune cells to sites of injury or infection like leukotrienes do. *Bradykinin* - Mainly functions in **pain sensation** and promoting **vascular permeability**, not as a direct chemotactic agent. - It influences inflammation but does not effectively recruit immune cells to tissues. *Leukotriene C4 and C3a* - **Leukotriene C4** is involved in bronchoconstriction, while **C3a** [1] has roles in the complement system but is less potent than C5a in chemotaxis. - These mediators have different primary roles in inflammation, lacking the specificity of B4 and C5a for leukocyte attraction. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 99-100. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 95-96.

Q: Interleukin responsible for Pyrexia is:

IL1. ***IL1*** - **Interleukin-1 (IL-1)** is a primary **endogenous pyrogen**, directly acting on the thermoregulatory center in the hypothalamus to induce fever. - It stimulates the production of **prostaglandin E2 (PGE2)**, which then alters the hypothalamic set point, leading to increased body temperature. *IL3* - **Interleukin-3 (IL-3)** is a **hematopoietic growth factor** that primarily stimulates the proliferation and differentiation of hematopoietic stem cells. - Its main role is in the development of various blood cell lineages, not directly in inducing fever. *IL4* - **Interleukin-4 (IL-4)** is a key cytokine in **allergic reactions** and **Th2 immune responses**, promoting B cell activation and IgE production. - It does not directly cause pyrexia; its primary functions are related to humoral immunity and immune regulation. *IL8* - **Interleukin-8 (IL-8)**, also known as **CXCL8**, is a potent **chemotactic factor** for neutrophils and other immune cells. - Its main function is to recruit inflammatory cells to sites of infection or injury, not to induce fever directly.

Q: What is the maximum tensile strength of a healed wound compared to the original tissue?

70-80% of original strength. ***70-80% of original strength*** - A healed wound, even under optimal conditions, can only achieve a maximum of **70-80%** of the tensile strength of the original **uninjured tissue** [1]. - This is because the repair process involves the formation of **fibrous scar tissue** which differs structurally from the original tissue, particularly in the organization and type of collagen fibers. *100% of original strength* - This option is incorrect because healed wounds, even completely mature ones, rarely regain the **full strength** of the original tissue [1]. - The replacement of damaged tissue with **scar tissue** inherently limits perfect functional and structural restoration. *50% of original strength* - While tensile strength gradually increases during wound healing, it typically exceeds **50%** as the wound matures. - This value is often seen in the **early stages** of healing but not as the maximum achievable strength. *None of the options* - This option is incorrect because **70-80% of original strength** is a well-established range for the maximum tensile strength of a healed wound. - This range reflects the physiological limitations of **scar tissue remodeling** and collagen deposition. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 119-121.

Q: Which of the following statements about interleukin-1 is false?

IL-1 inhibits IL-2 production by T-cells.. ***IL-1 inhibits IL-2 production by T-cells*** - This statement is false because **IL-1** actually **enhances the production of IL-2** by T-cells, which is crucial for T-cell proliferation and immune response. - **IL-1 acts synergistically with IL-6 and TNF-α** to promote inflammation and immune cell activation, where IL-2 plays a key role. *The primary source of IL-1 is the monocyte-macrophage system* - This statement is true; **monocytes and macrophages** are the main producers of **IL-1α and IL-1β** upon activation by various stimuli. - Other cells, such as neutrophils, dendritic cells, and endothelial cells, can also produce IL-1, but monocytes and macrophages are the predominant source. *IL-1 is an endogenous pyrogen* - This statement is true; **IL-1** is a potent **endogenous pyrogen** that acts on the hypothalamus to induce fever, a hallmark of the acute phase response. - It triggers prostaglandin synthesis in the hypothalamus, leading to an elevation in the body's thermoregulatory set point. *IL-1 promotes acute phase protein synthesis in the liver* - This statement is true; **IL-1** is a key mediator that stimulates **hepatocytes** to produce **acute phase proteins**, such as C-reactive protein and serum amyloid A. - This hepatic response is part of the innate immune system's effort to control infection and inflammation.

Q: Which of the following is not an acute phase reactant?

Endothelin. ***Endothelin*** - Endothelin is a **vasoconstrictive peptide** primarily involved in regulating **blood vessel tone** and blood pressure. - While it plays a role in processes like inflammation and tissue repair, it is not synthesized or regulated in the same rapid, systemic manner as a classic acute phase reactant. *C-reactive protein* - **C-reactive protein (CRP)** is a rapidly responding acute phase reactant produced by the liver in response to **inflammation**, infection, and tissue injury. - Its levels can rise dramatically within hours of an inflammatory stimulus and are used as a marker for disease activity. *Haptoglobin* - **Haptoglobin** is an acute phase reactant that binds to free **hemoglobin** released from red blood cells during hemolysis, preventing oxidative damage. - Its levels typically increase during acute inflammation or infection, although it can also decrease with severe hemolysis. *Fibrinogen* - **Fibrinogen** is a critical acute phase protein involved in the **coagulation cascade** and wound healing. - Its concentration increases significantly during acute inflammation, contributing to the elevated **erythrocyte sedimentation rate (ESR)**.

Question 1

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

Question 2

What is one of the primary functions of Interleukin-1 (IL-1)?

Accepted Answer

Acts as an endogenous pyrogen

Answer

Reduces inflammatory cell recruitment

Answer

Inhibits T cell proliferation

Answer

Suppresses antibody production

Question 3

First mediator of inflammation to be released is

Accepted Answer

Histamine

Answer

Nitric oxide

Answer

PAF

Answer

IL-1

Question 4

Rolling of leucocytes on endothelial cells is mediated by which of the following?

Accepted Answer

P-selectin

Answer

ICAM-1

Answer

Integrin

Answer

IL-8

Question 5

Which of the following is derived from fibroblast cells?

Accepted Answer

Collagen

Answer

MMP2

Answer

Angiopoietin

Answer

TGF-β

Question 6

Chemotaxis is mediated by-

Accepted Answer

Leukotriene B4 and C5a

Answer

Histamine

Answer

Leukotriene C4 and C3a

Answer

Bradykinin

Question 7

Interleukin responsible for Pyrexia is:

Accepted Answer

IL1

Answer

IL4

Answer

IL3

Answer

IL8

Question 8

What is the maximum tensile strength of a healed wound compared to the original tissue?

Accepted Answer

70-80% of original strength

Answer

100% of original strength

Answer

50% of original strength

Answer

None of the options

Question 9

Which of the following statements about interleukin-1 is false?

Accepted Answer

IL-1 inhibits IL-2 production by T-cells.

Answer

IL-1 is an endogenous pyrogen.

Answer

The primary source of IL-1 is the monocyte-macrophage system.

Answer

IL-1 promotes acute phase protein synthesis in the liver.

Question 10

Which of the following is not an acute phase reactant?

Accepted Answer

Endothelin

Answer

C-reactive protein

Answer

Haptoglobin

Answer

Fibrinogen

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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