Immunopathology Practice Questions

Q: Chediak-Higashi syndrome is characterized by a defect in which of the following?

Lysosome fusion. **Explanation:** **Chediak-Higashi Syndrome (CHS)** is an autosomal recessive disorder caused by a mutation in the **LYST gene** (Lysosomal Trafficking Regulator). This mutation leads to a defect in **microtubule-dependent phagosome-lysosome fusion** [1]. 1. **Why Option A is Correct:** The defect in the LYST protein prevents the proper trafficking and fusion of lysosomes with phagosomes [1]. This results in the formation of **giant lysosomal granules** in various cells (neutrophils, melanocytes, and platelets) because the organelles cannot be properly distributed or fused, leading to impaired intracellular killing of bacteria [1]. 2. **Why Other Options are Incorrect:** * **B & C (T-cells and B-cells):** CHS is primarily a defect of phagocytes (innate immunity) and natural killer (NK) cells. While it causes severe immunodeficiency, it is not a primary T-cell (e.g., DiGeorge) or B-cell (e.g., Bruton’s) deficiency. * **D (Complement):** Complement deficiencies (like C3 or C5-C9 defects) involve opsonization or membrane attack complex issues, not intracellular trafficking. **High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** Pathognomonic **giant granules** in neutrophils on peripheral smear [1]. * **Clinical Triad:** 1. **Partial Albinism** (melanocytes cannot transfer pigment granules to keratinocytes) [1]. 2. **Recurrent Pyogenic Infections** (Staph and Strep due to impaired chemotaxis/killing) [1]. 3. **Neurological symptoms** (peripheral neuropathy) [1]. * **Associated Feature:** Mild bleeding tendency due to defective dense granules in platelets [1]. * **Complication:** Risk of "Accelerated Phase" (Hemophagocytic Lymphohistiocytosis - HLH). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 245-246.

Question 1

Myasthenia gravis is associated with which of the following conditions?

Accepted Answer

Thymic hyperplasia

Answer

Thymoma

Answer

Thymic carcinoma

Answer

Lymphoma

Question 2

Chediak-Higashi syndrome is characterized by a defect in which of the following?

Accepted Answer

Lysosome fusion

Answer

T-cells

Answer

B-cells

Answer

Complement

Question 3

In acute solid organ Graft versus Host Disease, which of the following is not a characteristic feature?

Accepted Answer

Preformed antibodies are involved

Answer

Occurs within 100 days of transplantation

Answer

Skin is the most common organ involved

Answer

May lead to cholestatic jaundice

Question 4

MAST cells play a central role in the development of which type of hypersensitivity reaction?

Accepted Answer

Immediate

Answer

Antibody mediated

Answer

Cell mediated

Answer

Immune complex mediated

Question 5

For each patient with a specific medical condition, select the most likely immune dysfunction.

Accepted Answer

Mixed T- and B-cell deficiency/dysfunction

Answer

B-cell deficiency/dysfunction

Answer

T-lymphocyte deficiency/dysfunction

Answer

Neutropenia

Question 6

Which of the following is NOT a feature of antiphospholipid antibody syndrome?

Accepted Answer

Bleeding disorder

Answer

Recurrent fetal loss

Answer

Thrombotic disorder

Answer

Coagulation disorder

Question 7

T cell dependent tubercular antigens stimulate the production of which of the following antibodies?

Accepted Answer

IgG and IgA

Answer

IgM

Answer

IgG

Answer

IgG, IgM, IgA, IgE

Question 8

MALT is most commonly present in which part of the small intestine?

Accepted Answer

Ileum

Answer

Duodenum

Answer

Jejunum

Answer

Stomach

Question 9

CANCA is associated with which of the following conditions?

Accepted Answer

Wegener's granulomatosis

Answer

Microscopic polyangiitis

Answer

Churg-Strauss syndrome

Answer

Goodpasture syndrome

Question 10

Which of the following organs is NOT typically affected in Graft-Versus-Host disease?

Accepted Answer

Lung

Answer

Skin

Answer

Gastrointestinal tract

Answer

Liver

Immunopathology — MCQs

Immunopathology — MCQs

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