Immunopathology Practice Questions

Q: All of the following statements are true about Wiskott-Aldrich syndrome, except:

Autosomal recessive disorder. **Explanation:** Wiskott-Aldrich Syndrome (WAS) is a rare immunodeficiency characterized by the triad of **thrombocytopenia, eczema, and recurrent infections** [1]. **Why Option A is the correct answer (The Exception):** Wiskott-Aldrich Syndrome is an **X-linked recessive** disorder [1], not autosomal recessive. It is caused by a mutation in the *WAS* gene located on the short arm of the X chromosome (Xp11.23) [1]. This gene encodes the Wiskott-Aldrich Syndrome Protein (WASP), which is essential for actin cytoskeleton remodeling in hematopoietic cells. **Analysis of other options:** * **Option B (Low IgM):** Patients typically show a characteristic "inverted" immunoglobulin pattern: **Low IgM**, normal to high IgG, and **elevated IgA and IgE** levels [1]. * **Option C (Thrombocytopenia):** This is a hallmark feature. Patients present with micro-thrombocytopenia (small platelets) and are at high risk for mucosal bleeding and intracranial hemorrhage. * **Option D (Eczema):** Severe atopic dermatitis (eczema) is a classic component of the clinical triad, usually appearing in early infancy. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic (TIE):** **T**hrombocytopenia, **I**mmunodeficiency, **E**czema. * **Cellular Defect:** Impaired formation of the **immunological synapse** and defective migration of white blood cells [1]. * **Complications:** Increased risk for **B-cell lymphomas** [1] and autoimmune hemolytic anemia. * **Treatment:** Hematopoietic stem cell transplant (HSCT) is the definitive treatment [1]. * **Laboratory finding:** Small-sized platelets on peripheral smear (unique to WAS). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 250-251.

Q: Which of the following diseases is mediated through complement activation?

Necrotising vasculitis. The correct answer is **Necrotising vasculitis**. This condition is a classic example of **Type III Hypersensitivity reaction** (Immune-complex mediated) [2]. **1. Why Necrotising Vasculitis is Correct:** In Type III hypersensitivity, antigen-antibody complexes deposit in the walls of blood vessels. These complexes activate the **classical complement pathway**, leading to the generation of C3a and C5a (anaphylatoxins) [1]. These fragments recruit neutrophils, which release lysosomal enzymes and reactive oxygen species, causing "fibrinoid necrosis" of the vessel wall—the hallmark of necrotising vasculitis [2]. **2. Analysis of Incorrect Options:** * **Atopic Dermatitis (Option A):** This is primarily a **Type I Hypersensitivity** reaction mediated by IgE and mast cell degranulation, often associated with a Th2-dominant immune response. * **Graft versus Host Disease (Option B):** This is a **Type IV Hypersensitivity** (Cell-mediated) reaction. It occurs when donor T-cells recognize and attack the recipient's (host) HLA antigens. * **Photoallergy (Option C):** This is a form of delayed-type hypersensitivity (**Type IV**). It occurs when a substance on the skin becomes allergenic after exposure to UV light, triggering a T-cell mediated response. **3. NEET-PG High-Yield Pearls:** * **Complement Deficiencies:** Deficiency of early components (C1, C2, C4) is strongly associated with SLE-like syndromes due to failure to clear immune complexes. * **C3 levels:** Low serum C3 levels are a key diagnostic marker for active Type III reactions (e.g., Post-streptococcal glomerulonephritis or Systemic Lupus Erythematosus). * **Arthus Reaction:** A localized form of necrotising vasculitis caused by Type III hypersensitivity.

Question 1

Changes in which structural level of amyloid protein makes it insoluble?

Accepted Answer

Secondary structure

Answer

Primary structure

Answer

Tertiary structure

Answer

Quaternary structure

Question 2

Which of the following statements is NOT true regarding Natural Killer (NK) cells?

Accepted Answer

NK cells involve MHC antigens for killing micro-organisms.

Answer

NK cells are active against malignant cells.

Answer

NK cells are a first line of defense against viral infections.

Answer

No prior sensitization is required for NK cell activation.

Question 3

Which statement about pattern recognition receptors is false?

Accepted Answer

NOD-like receptors (NLRs) are cytosolic receptors, and their mutations can lead to autoimmune disorders.

Answer

Toll-like receptors are the best-known pattern recognition receptors.

Answer

Toll-like receptors are present in the plasma membrane and activate NF-κB and interferon regulatory factor.

Answer

RIG-like receptors (RLRs) are located in the cytosol and stimulate the production of antiviral cytokines.

Question 4

All of the following statements are true about Wiskott-Aldrich syndrome, except:

Accepted Answer

Autosomal recessive disorder

Answer

Low serum IgM level

Answer

Thrombocytopenia

Answer

Eczema

Question 5

Which of the following is NOT an immune complex hypersensitivity reaction?

Accepted Answer

Goodpasture syndrome

Answer

Systemic Lupus Erythematosus (SLE)

Answer

Autoimmune Hemolytic Anemia (AIHA) reaction

Answer

Post-streptococcal glomerulonephritis

Question 6

A 45-year-old woman with autoimmune hemolytic anemia presents with increasing fatigue. Which of the following mediators of inflammation is primarily responsible for antibody-mediated hemolysis in this patient?

Accepted Answer

Complement proteins

Answer

Arachidonic acid metabolites

Answer

Coagulation proteins

Answer

Kallikrein and kinins

Question 7

Acute cellular rejection following solid organ transplantation typically occurs when?

Accepted Answer

Between 5 and 30 days of transplantation

Answer

Within minutes to hours of transplantation

Answer

Within 48 hours of transplantation

Answer

Beyond 30 days after transplantation

Question 8

Which of the following conditions is an example of Type II hypersensitivity?

Accepted Answer

Pernicious anaemia

Answer

Serum sickness

Answer

Arthus phenomenon

Answer

Pathergy phenomenon

Question 9

Which of the following diseases is mediated through complement activation?

Accepted Answer

Necrotising vasculitis

Answer

Atopic dermatitis

Answer

Graft versus host disease

Answer

Photoallergy

Question 10

A 55-year-old male presented with dry mouth and rheumatoid arthritis with high titers of anti-SS-A and anti-SS-B antibodies. He was diagnosed with a minor salivary gland tumor. What is the earliest histologic finding in this condition?

Accepted Answer

Lymphocytes

Answer

Endothelial cells

Answer

Basophils

Answer

Eosinophils

Immunopathology — MCQs

Immunopathology — MCQs

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