Inflammation and Repair Practice Questions

Q: Mast cells secrete all except:

Bradykinin. **Explanation:** The correct answer is **D. Bradykinin**. **Why Bradykinin is the correct answer:** Mast cells are specialized immune cells found in connective tissue that contain granules rich in inflammatory mediators. While mast cells release a wide array of substances, **Bradykinin** is not secreted directly by them. Instead, Bradykinin is a plasma-derived peptide formed through the **Kinin-Kallikrein system**. It is produced when the enzyme kallikrein acts on high-molecular-weight kininogen (HMWK) in the plasma, typically triggered by tissue injury or inflammation. **Analysis of incorrect options:** * **A. Histamine:** This is the primary pre-formed mediator stored in mast cell granules. It causes vasodilation and increased vascular permeability during allergic reactions (Type I Hypersensitivity). * **B. Heparin:** Mast cells are a major source of endogenous heparin. It acts as an anticoagulant and serves as a structural matrix for storing other mediators within the granules. * **C. MIP (Macrophage Inflammatory Protein):** Mast cells secrete various cytokines and chemokines, including MIP-1α and MIP-1β, which help recruit other immune cells to the site of inflammation. **High-Yield Clinical Pearls for NEET-PG:** * **Mast Cell Triggers:** They are activated by the cross-linking of **IgE antibodies** bound to **FcεRI receptors** on their surface. * **Markers:** **Tryptase** is a specific marker for mast cell activation and is used clinically to confirm a diagnosis of anaphylaxis. * **Cromolyn Sodium:** This drug acts as a "Mast Cell Stabilizer" by preventing degranulation, commonly used in the management of asthma and allergic rhinitis. * **Location:** Mast cells are most abundant in areas exposed to the external environment, such as the skin, lungs, and gastrointestinal tract.

Q: Caseous granuloma is seen in which of the following conditions?

Histoplasmosis. **Explanation:** **Caseous necrosis** is a form of cell death characterized by a "cheese-like" appearance, typically resulting from a granulomatous inflammatory response. While classically associated with *Mycobacterium tuberculosis*, it is also a hallmark of certain fungal infections, most notably **Histoplasmosis**. 1. **Why Histoplasmosis is correct:** *Histoplasma capsulatum* is a dimorphic fungus that triggers a cell-mediated immune response. This leads to the formation of granulomas that frequently undergo central caseous necrosis, making it histologically indistinguishable from tuberculosis without special stains (like GMS or PAS). 2. **Why the other options are incorrect:** * **Silicosis:** Characterized by **fibrotic nodules** (concentric "onion-skin" collagen layers) rather than caseous necrosis. * **Sarcoidosis:** The classic pathological finding is **non-caseating granulomas**. The presence of caseation usually rules out a diagnosis of sarcoidosis. * **Foreign body reaction:** Results in **non-caseating granulomas** containing foreign body giant cells (with haphazardly arranged nuclei) surrounding exogenous material. **High-Yield Clinical Pearls for NEET-PG:** * **Caseating Granulomas:** Think Tuberculosis, Histoplasmosis, Coccidioidomycosis, and occasionally Syphilis (gumma). * **Non-Caseating Granulomas:** Think Sarcoidosis, Crohn’s disease, Berylliosis, and Lepromatous leprosy. * **Histoplasmosis Key Visual:** Look for small, intracellular ovoid yeast cells within macrophages (narrow-based budding). * **Staining:** Use **Gomori Methenamine Silver (GMS)** or **Periodic Acid-Schiff (PAS)** to identify the fungal etiology in caseating lesions.

Q: Which cytokine has a predominant anti-inflammatory action?

TGF-beta. **Explanation:** The balance between pro-inflammatory and anti-inflammatory cytokines is crucial for immune homeostasis. **TGF-beta (Transforming Growth Factor-beta)** is a potent **anti-inflammatory** cytokine. It functions by inhibiting the proliferation and activation of lymphocytes (T-cells and B-cells) and suppressing the production of pro-inflammatory cytokines [1]. Additionally, it plays a vital role in tissue repair and fibrosis by stimulating collagen synthesis [1]. Along with **IL-10**, TGF-beta is considered a primary mediator of immune tolerance and resolution of inflammation. **Analysis of Incorrect Options:** * **Interleukin 6 (IL-6):** A classic **pro-inflammatory** cytokine. It is a major inducer of the "acute phase response" in the liver (CRP production) and is involved in fever and the transition from innate to adaptive immunity [1]. * **GM-CSF (Granulocyte-Macrophage Colony-Stimulating Factor):** A growth factor that stimulates the bone marrow to produce granulocytes and monocytes [1]. It acts as a **pro-inflammatory** mediator by enhancing the survival and activation of mature macrophages and neutrophils. * **TNF-Alpha (Tumor Necrosis Factor-alpha):** A "master" **pro-inflammatory** cytokine produced primarily by macrophages. It mediates septic shock, induces endothelial activation, and recruits leukocytes to sites of infection [1]. **High-Yield Clinical Pearls for NEET-PG:** * **The "Anti-inflammatory Duo":** Always remember **IL-10 and TGF-beta** as the primary anti-inflammatory cytokines. * **TGF-beta Dual Role:** While anti-inflammatory, it is the most important cytokine for **fibrosis** (stimulates fibroblasts) [1]. * **IL-1 and TNF-alpha:** These are the primary mediators of acute inflammation [1]. * **IL-8:** The most potent chemotactic factor for **neutrophils**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 111-116.

Q: Which of the following is a chemoattractant?

C5a. **Explanation:** The complement system is a crucial component of innate immunity, consisting of a cascade of proteins that enhance the ability of antibodies and phagocytic cells to clear pathogens. **Why C5a is Correct:** C5a is a potent **anaphylatoxin** and the most powerful **chemoattractant** of the complement system. During the activation of the complement cascade, C5 is cleaved into C5a and C5b. C5a acts as a chemical signal that recruits neutrophils, monocytes, and macrophages to the site of inflammation (chemotaxis). It also triggers mast cell degranulation, leading to increased vascular permeability. **Why the other options are incorrect:** * **C1:** This is the starting component of the Classical Pathway. It recognizes antigen-antibody complexes but does not possess chemotactic activity. * **C3:** This is the most abundant complement protein. While its cleavage product **C3a** is an anaphylatoxin, C3 itself is an inactive precursor. Its other product, **C3b**, is primarily involved in **opsonization** (tagging pathogens for phagocytosis). * **C2:** This is a component of the Classical and Lectin pathways. Its cleavage products (C2a/C2b) are involved in forming the C3 convertase but do not act as chemoattractants. **High-Yield NEET-PG Pearls:** * **Potency of Chemoattractants:** C5a > LTB4 (Leukotriene B4) > IL-8 > Bacterial products (N-formyl peptides). * **Opsonization:** C3b is the major opsonin. * **Membrane Attack Complex (MAC):** Formed by C5b-C9; responsible for osmotic lysis of gram-negative bacteria. * **Anaphylatoxins:** C5a > C3a > C4a (in order of potency). * **Deficiency:** C5-C9 deficiency increases susceptibility to *Neisseria* infections.

Q: Which cells secrete IL-1 and TNF-alpha during inflammation?

Activated macrophages. **Explanation:** **Correct Answer: C. Activated macrophages** The primary source of the major pro-inflammatory cytokines, **Interleukin-1 (IL-1)** and **Tumor Necrosis Factor-alpha (TNF-̑)**, is activated macrophages [1]. These cytokines are released in response to bacterial products (like LPS), immune complexes, or physical injury. They act as "master regulators" of inflammation by inducing endothelial activation, stimulating the synthesis of acute-phase proteins in the liver, and triggering systemic effects like fever (by acting on the hypothalamus). **Analysis of Incorrect Options:** * **A. Plasma cells:** These are terminally differentiated B-cells primarily responsible for the secretion of **antibodies (immunoglobulins)**, not pro-inflammatory cytokines. * **B. Lymphocytes:** While T-lymphocytes can secrete TNF, their primary products are interleukins like IL-2, IL-4, and IFN-̑. Macrophages remain the most potent and prolific source of IL-1 and TNF-̑ in the acute inflammatory milieu [1]. * **D. Platelets:** Platelets primarily release growth factors (like **PDGF** and **TGF-̒**) and vasoactive amines (serotonin) from their granules to assist in clotting and wound healing. **High-Yield NEET-PG Pearls:** * **Fever Induction:** IL-1 and TNF-̑ induce fever by increasing **PGE2** synthesis in the hypothalamus. * **Cachexia:** TNF-̑ is also known as **"Cachectin"** because it promotes weight loss and anorexia by suppressing appetite and mobilizing fat stores during chronic inflammation or malignancy. * **Septic Shock:** High concentrations of TNF-̑ are the primary mediators of the systemic hypotension and metabolic disturbances seen in septic shock. * **Inhibitors:** Drugs like **Etanercept** and **Infliximab** are TNF-antagonists used in treating rheumatoid arthritis and IBD. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 105-106.

Question 1

Mast cells secrete all except:

Accepted Answer

Bradykinin

Answer

Histamine

Answer

Heparin

Answer

MIP

Question 2

Caseous granuloma is seen in which of the following conditions?

Accepted Answer

Histoplasmosis

Answer

Silicosis

Answer

Sarcoidosis

Answer

Foreign body reaction

Question 3

A 9-year-old boy is admitted with acute abdominal pain localized in the right iliac fossa. He is pyrexial with localized peritonism in the RIF. Which type of cell is primarily involved in the inflammatory response causing these signs?

Accepted Answer

Neutrophils

Answer

Lymphocytes

Answer

Macrophages

Answer

Monocytes

Question 4

Which cytokine has a predominant anti-inflammatory action?

Accepted Answer

TGF-beta

Answer

Interleukin 6

Answer

GM-CSF

Answer

TNF-Alpha

Question 5

Which of the following is a chemoattractant?

Accepted Answer

C5a

Answer

Cl

Answer

C3

Answer

C2

Question 6

Which cells secrete IL-1 and TNF-alpha during inflammation?

Accepted Answer

Activated macrophages

Answer

Plasma cells

Answer

Lymphocytes

Answer

Platelets

Question 7

Delayed prolonged increase in vascular permeability in inflammation is due to?

Accepted Answer

Interleukin 1 mediated endothelial retraction

Answer

Increased transcytosis

Answer

Leakage from newly formed blood vessels

Answer

Release of histamine causing endothelial contraction

Question 8

All are major cytokines in chronic inflammation except?

Accepted Answer

IL-6

Answer

IL-12

Answer

IFN-y

Answer

IL-17

Question 9

Candida infections are commonly seen in patients with which of the following conditions?

Accepted Answer

Myeloperoxidase deficiency

Answer

Chronic granulomatous disease

Answer

Chediak-Higashi syndrome

Answer

Lazy leukocyte syndrome

Question 10

Which of the following is NOT a positive acute-phase reactant?

Accepted Answer

Transthyretin

Answer

Serum Amyloid A protein

Answer

Fibrinogen

Answer

Hepcidin

Inflammation and Repair — MCQs

Inflammation and Repair — MCQs

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