# Inflammation and Repair for NEET PG Pathology: Leukocyte Steps, Mediators, Granulomas, Phagocyte Defects, Wound Healing Source: https://tracknation.in/story/inflammation-and-repair-for-neet-pg-pathology-leukocyte-steps-mediators-granulomas-phagocyte-defects-wound-healing (TrackNation β€” free UPSC notes with PYQs) > NEET PG Pathology: cardinal signs, exudate vs transudate, leukocyte rolling, adhesion, chemotaxis and respiratory burst, mediators and fever, CRP and ESR, LAD, CGD and ChΓ©diak-Higashi, granulomas and giant cells, TB vs sarcoidosis, granulation tissue, keloid vs hypertrophic scar and scurvy, with a diagram, hooks, vignette MCQs and cards. ## Start Here 🎯 **Exam priority: High.** *Expect: steps of leukocyte emigration and their molecules, mediator actions, pyrogens, the three phagocyte defects by their clues, giant-cell types, caseating vs non-caseating granulomas, and keloid vs hypertrophic scar.* CBME mapping: **PA 3.1–3.4, 4.1**. *Leukocyte steps, mediators, granulomas, phagocyte defects and healing. Drawn by TrackNation.* ## Acute Inflammation - Cardinal signs: pain, heat, redness, swelling and loss of function. - **Exudate**: fluid, cells and proteins slowly leaving vessels in inflamed tissue. **Transudate**: thin, watery, few cells or proteins. Oedema = abnormal fluid in tissues or body cavities. - **Neutrophil journey**: rolling on endothelium (selectins) β†’ activation by chemokines, flattening and firm attachment (integrins) β†’ chemotaxis up a chemical gradient (e.g. IL-8) β†’ phagocytosis β†’ killing by the **respiratory burst** (NADPH oxidase makes superoxide). | **Mediator (MeSH/MSD)** | **Main action** | | Histamine (from histidine) | Vasodilator, bronchoconstrictor | | Bradykinin | Arteriolar dilation, more capillary permeability (short-lived) | | Prostaglandins (COX pathway) | Potent mediators; PGE2 drives fever | | Leukotrienes (5-lipoxygenase) | Immediate hypersensitivity, inflammation | | Platelet-activating factor | Platelet aggregation, anaphylactic symptoms | | IL-8 (CXC chemokine) | Neutrophil chemotaxis | | IL-1, TNF-Ξ±, IL-6 | Endogenous pyrogens | | C3a, C5a | Anaphylatoxins | ## Fever and the Acute-Phase Response - Exogenous pyrogens (e.g. endotoxin, the lipopolysaccharide of Gram-negative bacteria) release endogenous pyrogens β€” IL-1, TNF-Ξ±, IL-6 β€” and PGE2 resets the hypothalamic thermostat. A rise without a reset set point is **hyperthermia**, not fever. - The liver changes acute-phase protein output; **CRP** rises in inflammation and tissue damage. **ESR** measures how fast red cells settle. Leukocytosis is a transient rise in white cells. An **abscess** is a collection of pus. ## When Phagocytes Fail | **Phagocyte defect (MSD/MeSH)** | **Defect** | **Clue** | | Leukocyte adhesion deficiency (AR) | Ξ²2 integrins (CD11/CD18) β†’ neutrophils cannot leave vessels | No pus, high WBC, cord separation > 3 weeks | | Chronic granulomatous disease (> 50% X-linked) | No oxidative burst (NADPH oxidase) β†’ ingest but cannot kill | Catalase-positive infections, Aspergillus; DHR/NBT test | | ChΓ©diak-Higashi syndrome (AR) | Abnormal lysosomes | Oculocutaneous albinism, pyogenic infections, lymphoreticular cancers | ## Chronic and Granulomatous Inflammation - A **granuloma** is a small nodule of grouped mononuclear phagocytes. **Epithelioid cells** are macrophages activated by prolonged antigen exposure; they fuse into giant cells. - **Langhans giant cells**: nuclei in a peripheral horseshoe β€” TB, syphilis, sarcoidosis, deep fungal infection. **Foreign-body giant cells**: nuclei scattered irregularly, around foreign material. - **TB**: epithelioid granulomas with caseous centres. **Sarcoidosis**: non-caseating granulomas, cause unknown, mostly lungs and lymph nodes; macrophages activate vitamin D β†’ hypercalcaemia; ACE may be raised but is non-specific. ## Repair and Healing - **Regeneration** replaces tissue; **repair** restores integrity with connective tissue. **Granulation tissue** = new capillaries with lymphocytes, macrophages and plasma cells on a healing surface. Contractile **myofibroblasts** work in granulation tissue and in fibrosis. Collagen is about one-third of body protein. - **Keloid**: fibroblastic overgrowth that extends beyond the wound margins (earlobes, shoulders, upper arms, chest). **Hypertrophic scar**: stays within the wound and may regress. **Fibrosis**: fibrous tissue invading an organ after injury. - **Scurvy** (vitamin C deficiency): defective collagen in small vessels β€” bleeding, spongy gums, anaemia, impaired wound healing. ## Traps the Examiner Sets - Selectins = rolling; integrins = firm adhesion (LAD = CD18). - CGD: phagocytes engulf but cannot kill; catalase-positive bugs. LAD: no pus and late cord fall. - Langhans = horseshoe nuclei; foreign-body = scattered nuclei. - Keloid crosses the wound edge; hypertrophic scar does not. ## Memory Hooks & Shortcuts *Shortcuts to lock in this article's numbers and lists. Each one only re-packages facts proven above.* - 🧠 **Selectins Slow them, Integrins Imprison them** β€” rolling vs firm adhesion - 🧠 **Eight calls the neutrophils to the fight** β€” IL-8 chemotaxis - 🧠 **CGD: Can Grab, Doesn't digest** β€” CGD mechanism - 🧠 **LAD: Leukocytes Aren't Departing (no pus, late cord)** β€” leukocyte adhesion deficiency - 🧠 **Langhans = Lucky horseshoe** β€” Langhans giant cells - 🧠 **Keloid Keeps going beyond the edge** β€” keloid vs hypertrophic - 🧠 **1, 6 and TNF light the fire** β€” pyrogens ## Rapid-Revision Cards - Pain, heat, redness, swelling, loss of function. - Cells + protein vs thin, watery, few cells. - Selectins. - Integrins (CD11/CD18). - IL-8. - NADPH oxidase β†’ superoxide. - Vasodilator, bronchoconstrictor. - Dilation + permeability, short-lived. - Prostaglandins vs leukotrienes. - IL-1, TNF-Ξ±, IL-6 β†’ PGE2. - High temperature, set point unchanged. - Acute-phase protein / red-cell settling. - AR; CD18; no pus; cord > 3 weeks. - > 50% X-linked; catalase+; DHR/NBT. - AR; albinism; abnormal lysosomes. - Activated macrophage. - Horseshoe nuclei β€” TB, sarcoid. - Scattered nuclei. - Non-caseating; vitamin D activation; ACE non-specific. - Capillaries + lymphocytes, macrophages, plasma cells. - Beyond vs within margins. - Collagen defect; gums, bleeding, poor healing. ## Sources *Facts in this article were checked against these documents.* - Medical Subject Headings (MeSH) scope notes β€” US National Library of Medicine, accessed 2026 (link) - MSD Manual Professional: Fever; Chronic Granulomatous Disease; Leukocyte Adhesion Deficiency; Sarcoidosis; Keloids; Vitamin C Deficiency β€” Merck & Co. (MSD Manuals), reviewed 2025–26 (link) - MSD Manual Professional: Complement System; Tuberculosis β€” Merck & Co. (MSD Manuals), reviewed 2025–26 (link) - Competency Based Undergraduate Curriculum, Pathology (PA 3–4) β€” National Medical Commission, 2024 ## Test Yourself: Practice Questions Thirty-two questions in NEET PG style, most of them clinical vignettes. ## Practice Questions (NEET PG pattern) *Original questions written in the style of the exam: +4 for a correct answer, βˆ’1 for a wrong one. Every answer was checked against the sources listed above. NEET PG papers are not published by NBEMS, so these are not past-paper questions.* **Q1.** The classic signs of acute inflammation are - (a) fever only - (b) pallor, cold and numbness - (c) itching and scaling - (d) pain, heat, redness, swelling and loss of function **Answer: (d)** β€” MeSH definition of inflammation. **Q2.** Fluid from a patient's swollen ankles is thin and watery with very few cells and little protein. It is - (a) an exudate - (b) pus - (c) a transudate - (d) chyle **Answer: (c)** β€” Exudates carry cells and proteins from inflamed vessels. **Q3.** The first loose contact of neutrophils with inflamed endothelium, in which they tumble along the vessel wall, depends mainly on - (a) selectins - (b) integrins - (c) immunoglobulins - (d) collagen **Answer: (a)** β€” Rolling; then chemokine activation and firm adhesion. **Q4.** An infant has recurrent infections without pus, a persistently high white count and the umbilical cord fell off after 4 weeks. The defect is in - (a) lysosomes - (b) NADPH oxidase - (c) Ξ²2 integrins (CD11/CD18) β€” leukocyte adhesion deficiency - (d) complement C5 **Answer: (c)** β€” Neutrophils cannot leave vessels; autosomal recessive. **Q5.** The chemokine that chiefly draws neutrophils to a site of acute inflammation is - (a) IL-10 - (b) IL-4 - (c) IL-8 (a CXC chemokine) - (d) interferon-Ξ³ **Answer: (c)** β€” Chemotaxis follows a chemical gradient. **Q6.** Neutrophils kill ingested bacteria by a sudden rise in oxygen use that makes superoxide. The enzyme is - (a) myeloperoxidase alone - (b) cyclooxygenase - (c) NADPH oxidase (respiratory burst) - (d) lysozyme **Answer: (c)** β€” Defective in chronic granulomatous disease. **Q7.** A boy has recurrent abscesses and lung granulomas; cultures grow Staphylococcus aureus and Aspergillus. The DHR test shows no oxidative burst. The diagnosis is - (a) complement C5 deficiency - (b) chronic granulomatous disease - (c) ChΓ©diak-Higashi syndrome - (d) leukocyte adhesion deficiency **Answer: (b)** β€” Catalase-positive organisms; Aspergillus is the leading cause of death. **Q8.** In chronic granulomatous disease, phagocytes - (a) ingest bacteria but fail to kill and digest them - (b) are absent - (c) cannot leave blood vessels - (d) cannot ingest bacteria **Answer: (a)** β€” More than half of cases are X-linked recessive. **Q9.** A child with oculocutaneous albinism has recurrent pyogenic infections; many cell types contain abnormal lysosomes. The diagnosis is - (a) Down syndrome - (b) ChΓ©diak-Higashi syndrome (autosomal recessive) - (c) chronic granulomatous disease - (d) leukocyte adhesion deficiency **Answer: (b)** β€” High incidence of lymphoreticular neoplasms. **Q10.** Bradykinin contributes to inflammatory swelling by - (a) arteriolar dilation and increased capillary permeability - (b) neutrophil chemotaxis only - (c) platelet aggregation - (d) fever only **Answer: (a)** β€” Potent but short-lived. **Q11.** Prostaglandins are made from arachidonic acid by the - (a) kinin system - (b) cyclooxygenase pathway - (c) complement cascade - (d) 5-lipoxygenase pathway **Answer: (b)** β€” Leukotrienes come from 5-lipoxygenase. **Q12.** Leukotrienes are formed from arachidonic acid by - (a) 5-lipoxygenase - (b) phospholipase only - (c) NADPH oxidase - (d) cyclooxygenase **Answer: (a)** β€” Involved in immediate hypersensitivity and inflammation. **Q13.** A phospholipid mediator from platelets, basophils and macrophages that causes platelet aggregation and anaphylactic hypotension is - (a) IL-8 - (b) histamine - (c) bradykinin - (d) platelet-activating factor **Answer: (d)** β€” MeSH. **Q14.** The endogenous pyrogens that cause fever in infection are - (a) IL-4 and IL-13 - (b) IgE and histamine - (c) IL-10 and TGF-Ξ² - (d) IL-1, TNF-Ξ± and IL-6 (acting through PGE2) **Answer: (d)** β€” They reset the hypothalamic set point. **Q15.** A patient's temperature is 41 Β°C but the hypothalamic set point has not been reset. This is - (a) fever from endogenous pyrogens - (b) a PGE2-mediated fever - (c) hyperthermia, not fever - (d) septic fever **Answer: (c)** β€” Fever requires a reset set point. **Q16.** The classic exogenous pyrogen from Gram-negative bacteria is - (a) flagellin only - (b) peptidoglycan only - (c) teichoic acid - (d) lipopolysaccharide (endotoxin) **Answer: (d)** β€” S. aureus toxic shock toxin is another. **Q17.** A plasma protein made by the liver that rises during inflammation and after tissue damage is - (a) C-reactive protein - (b) albumin - (c) prealbumin - (d) transferrin **Answer: (a)** β€” Acute-phase proteins can rise or fall. **Q18.** The ESR measures - (a) white cell count - (b) the rate at which red cells settle in blood - (c) CRP concentration - (d) platelet function **Answer: (b)** β€” MeSH: Blood Sedimentation. **Q19.** A granuloma is - (a) a scar - (b) a blood clot - (c) a collection of pus - (d) a small nodular collection of grouped mononuclear phagocytes **Answer: (d)** β€” Caused by infectious and non-infectious agents. **Q20.** Epithelioid cells in a granuloma are - (a) epithelial cells - (b) plasma cells - (c) neutrophils - (d) activated macrophages after prolonged antigen stimulation **Answer: (d)** β€” They fuse to form giant cells. **Q21.** A lymph node granuloma contains multinucleated giant cells with nuclei arranged in a peripheral horseshoe. These are - (a) Langhans giant cells - (b) foreign-body giant cells - (c) Touton cells - (d) Reed-Sternberg cells **Answer: (a)** β€” Seen in TB, syphilis, sarcoidosis, deep fungal infection. **Q22.** Around foreign material in the skin, giant cells with many nuclei scattered irregularly in the cytoplasm are - (a) Langhans giant cells - (b) megakaryocytes - (c) foreign-body giant cells - (d) Reed-Sternberg cells **Answer: (c)** β€” They form around exogenous material. **Q23.** A young adult with lung and lymph node involvement has granulomas without central necrosis; tests for infection are negative. The likely diagnosis is - (a) sarcoidosis - (b) tuberculosis - (c) foreign-body reaction - (d) lymphoma **Answer: (a)** β€” Non-caseating granulomas; lungs and lymphatics most often. **Q24.** A patient with sarcoidosis has hypercalcaemia. The mechanism is - (a) bone metastases - (b) macrophages convert vitamin D to its active 1,25 form - (c) thiazide use - (d) PTH-related peptide from tumour **Answer: (b)** β€” Hypercalciuria may occur even with normal serum calcium. **Q25.** In suspected sarcoidosis, a raised serum ACE is - (a) diagnostic - (b) a marker of TB - (c) always present - (d) suggestive but non-specific **Answer: (d)** β€” Also raised in hyperthyroidism, diabetes, silicosis, mycobacterial and fungal disease. **Q26.** The pink, granular tissue on the base of a healing ulcer is made of - (a) fat cells - (b) epithelium only - (c) dense mature collagen only - (d) new capillaries with lymphocytes, macrophages and plasma cells **Answer: (d)** β€” Granulation tissue. **Q27.** Spindle-shaped cells with contractile proteins that help heal wounds and also appear in fibrosis are - (a) plasma cells - (b) epithelioid cells - (c) mast cells - (d) myofibroblasts **Answer: (d)** β€” Found in granulation tissue. **Q28.** Months after ear piercing, a firm scar grows well beyond the edges of the original wound. This is - (a) a hypertrophic scar - (b) a granuloma - (c) granulation tissue - (d) a keloid **Answer: (d)** β€” Hypertrophic scars stay within the wound and may regress. **Q29.** An elevated scar that stays within the wound margins and later regresses by itself is - (a) a hypertrophic scar - (b) fibrosis - (c) a keloid - (d) a sarcoma **Answer: (a)** β€” MeSH. **Q30.** A man on a very poor diet has bleeding gums, easy bruising and wounds that will not heal. The defect is in - (a) clotting factor VIII - (b) collagen formation (vitamin C deficiency) - (c) iron absorption - (d) platelet production **Answer: (b)** β€” Scurvy: defective collagen in small vessels. **Q31.** Collagen makes up about what fraction of total body protein? - (a) half - (b) one-third - (c) two-thirds - (d) one-tenth **Answer: (b)** β€” Main constituent of skin, connective tissue, bone and teeth. **Q32.** A localised collection of pus in a tissue is called - (a) a transudate - (b) a keloid - (c) a granuloma - (d) an abscess **Answer: (d)** β€” Usually with signs of infection. ### Active Recall From memory: list the cardinal signs and contrast exudate and transudate; describe neutrophil rolling, adhesion, chemotaxis and killing with their molecules; give the action of each major mediator and the pyrogens; match LAD, CGD and ChΓ©diak-Higashi to their defects; describe granulomas and giant cells in TB and sarcoidosis; and explain granulation tissue, keloids and scurvy.