Immunopathology Practice Questions

Q: Which antinuclear antibody is specific for Systemic Lupus Erythematosus (SLE)?

Anti ds DNA. **Explanation:** In Systemic Lupus Erythematosus (SLE), the production of autoantibodies against nuclear antigens is the hallmark of the disease [1]. **Why Anti-dsDNA is correct:** While many antibodies appear in SLE, **Anti-dsDNA** and **Anti-Smith (Sm)** antibodies are considered **highly specific** for the diagnosis [1]. Anti-dsDNA levels often correlate with disease activity, particularly the development of lupus nephritis, making it useful for both diagnosis and monitoring. **Analysis of Incorrect Options:** * **Anti-nuclear antibodies (ANA):** This is the **best screening test** for SLE due to its very high sensitivity (95-99%) [1]. However, it lacks specificity as it is positive in many other autoimmune conditions (Scleroderma, RA, Sjögren’s) and even in healthy individuals [1]. * **Anti-centromere antibody:** This is highly specific for **Limited Cutaneous Systemic Sclerosis** (formerly CREST syndrome), not SLE [1]. * **Anti-histone antibody:** This is the characteristic marker for **Drug-Induced Lupus (DILE)** [1]. While it can be present in systemic SLE, its presence in the absence of other SLE-specific markers strongly suggests a drug-induced etiology (e.g., Hydralazine, Procainamide). **NEET-PG High-Yield Pearls:** * **Most Sensitive Test for SLE:** ANA (Indirect Immunofluorescence is the gold standard). * **Most Specific Tests for SLE:** Anti-dsDNA and Anti-Smith. * **Antibody for Neonatal Lupus/Congenital Heart Block:** Anti-Ro (SSA) and Anti-La (SSB). * **Antibody for Libman-Sacks Endocarditis/Thrombosis:** Anti-phospholipid antibodies (APLA). * **Drug-Induced Lupus:** Anti-histone positive; Anti-dsDNA usually negative; CNS and Renal involvement are rare. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 226-230.

Q: Which of the following is seen in antiphospholipid antibody syndrome?

Anti glycoproteins antibody. **Explanation:** **Antiphospholipid Antibody Syndrome (APS)** is an autoimmune prothrombotic state characterized by recurrent arterial or venous thrombosis and pregnancy complications [1]. **Why Option D is correct:** The term "antiphospholipid" is slightly misleading because the antibodies do not bind directly to phospholipids. Instead, they target **plasma proteins (glycoproteins)** that are bound to anionic phospholipids. The most clinically significant target is **Apolipoprotein H**, commonly known as **Beta-2 Glycoprotein I (β2-GPI)** [1]. Other targets include prothrombin. Therefore, APS is fundamentally characterized by the presence of **anti-glycoprotein antibodies** [1]. **Analysis of Incorrect Options:** * **Option A (Beta 2 microglobulin):** This is a component of MHC Class I molecules and a marker for cell turnover (often elevated in multiple myeloma or lymphoma). It is frequently confused with *Beta-2 Glycoprotein I*, which is the actual target in APS. * **Option B (Anti-nuclear antibody - ANA):** While ANA is the screening test for Systemic Lupus Erythematosus (SLE), and APS can occur secondary to SLE, ANA itself is not diagnostic or specific for APS. * **Option C (Anti-centromere antibody):** This is a specific marker for **Limited Cutaneous Systemic Sclerosis (CREST syndrome)**, not APS. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Triad (Laboratory):** Lupus anticoagulant (LA), Anti-cardiolipin antibodies (aCL), and Anti-β2-glycoprotein I antibodies [1]. * **False Positive VDRL:** Patients with APS often show a false positive syphilis test (VDRL/RPR) because the reagent contains cardiolipin. * **Coagulation Paradox:** In vitro, Lupus Anticoagulant **prolongs aPTT** (acting as an anticoagulant), but in vivo, it is highly **prothrombotic** [1]. * **Clinical Hallmark:** Recurrent miscarriages and "white clots" (arterial thrombosis) [1].

Q: Which of the following cytokines does not play a role in the production, maintenance, or activation of lymphocytes?

IL-12. **Explanation:** The correct answer is **IL-12**. While IL-12 is a critical cytokine in the immune response, its primary role is the **differentiation** of naive T-cells into Th1 cells [1] and the activation of Natural Killer (NK) cells. It is produced by antigen-presenting cells (macrophages and dendritic cells) rather than being a primary driver for the production or maintenance of the lymphocyte pool itself. **Analysis of Options:** * **IL-1 (Incorrect):** Produced by macrophages, IL-1 acts as a costimulator for **T-cell activation** and promotes the proliferation of B-cells. It is essential for the early stages of lymphocyte response. * **IL-2 (Incorrect):** Known as the **"T-cell growth factor,"** it is the most critical cytokine for the proliferation (production/maintenance) of T-lymphocytes [1]. It acts in an autocrine fashion to drive clonal expansion [1]. * **IL-4 (Incorrect):** Produced by Th2 cells, it is vital for **B-cell activation**, proliferation, and isotype switching to IgE. It also promotes the differentiation of naive T-cells into Th2 cells. **High-Yield NEET-PG Pearls:** * **IL-2** is the target of immunosuppressants like Cyclosporine and Tacrolimus (which inhibit IL-2 production via calcineurin inhibition). * **IL-7** (not listed) is the primary cytokine responsible for the **maintenance** of memory T-cells and early lymphoid progenitors in the bone marrow. * **IL-12 deficiency** leads to disseminated mycobacterial infections due to the inability to mount a Th1/IFN-$\gamma$ response. * **IL-1, IL-6, and TNF-$\alpha$** are the "pro-inflammatory triad" responsible for the acute phase response and fever. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 206-218.

Question 1

What does epitope spreading refer to?

Accepted Answer

A mechanism for the persistence and evolution of autoimmune disease.

Answer

A mechanism of spread of malignant tumors.

Answer

A mechanism of HIV dissemination.

Answer

A mechanism of apoptosis.

Question 2

A 60-year-old female with a 8-year history of renal failure on hemodialysis develops Carpal Tunnel syndrome. Which of the following types of amyloid will be associated with this condition?

Accepted Answer

Beta-2 microglobulin

Answer

Amyloid light chain

Answer

ATTR

Answer

Serum amyloid associated protein

Question 3

In Henoch-Schonlein purpura, which immunoglobulins and complement components are involved?

Accepted Answer

IgA, C3

Answer

IgG, C3

Answer

IgA, C1

Answer

IgG, C1

Question 4

Which of the following statements about macrophages is false?

Accepted Answer

Involved in Type III hypersensitivity

Answer

Derived from monocytes

Answer

Harbor Mycobacteria

Answer

Produce TNF and interleukins

Question 5

Which antinuclear antibody is specific for Systemic Lupus Erythematosus (SLE)?

Accepted Answer

Anti ds DNA

Answer

Anti nuclear antibodies

Answer

Anti centromere antibody

Answer

Anti histone antibody

Question 6

Which of the following is seen in antiphospholipid antibody syndrome?

Accepted Answer

Anti glycoproteins antibody

Answer

Beta 2 microglobulin antibody

Answer

Anti nuclear antibody

Answer

Anti centromere antibody

Question 7

A boy presents with shortness of breath after being injected with penicillin, with no prior history of allergy. Examination 48 hours later reveals destruction of his RBCs, leading to a diagnosis of autoimmune hemolytic anemia (AIHA). What type of hypersensitivity reaction is responsible?

Accepted Answer

Type II

Answer

Type I

Answer

Type III

Answer

Type IV

Question 8

Aspiration of fluid around the knee joint of a diabetic patient undergoing dialysis would show which of the following?

Accepted Answer

Beta-2 microglobulin

Answer

AA amyloid

Answer

AL amyloid

Answer

Lactoferrin

Question 9

Which of the following cytokines does not play a role in the production, maintenance, or activation of lymphocytes?

Accepted Answer

IL-12

Answer

IL-1

Answer

IL-2

Answer

IL-4

Question 10

A previously healthy eight-year-old boy presented to the emergency department with high-grade fever, arthralgia, pruritic erythematous rash, and lymphadenopathy. He had completed 8 days of a 10-day course of cefaclor for an upper respiratory tract infection. Which of the following possibilities should be initially suspected?

Accepted Answer

Type III Hypersensitivity Reaction

Answer

Kawasaki Disease

Answer

Anaphylaxis

Answer

Henoch-Schonlein purpura

Immunopathology — MCQs

Immunopathology — MCQs

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