Immunopathology Practice Questions

Q: Hyperacute rejection occurs within:

12 hours. **Explanation:** **Hyperacute rejection** is a Type II hypersensitivity reaction characterized by its rapid onset, occurring within **minutes to a few hours** (typically up to 12–24 hours) after transplantation. It is mediated by **pre-formed antibodies** (IgG) in the recipient's serum against the donor's antigens (usually ABO blood group antigens or HLA Class I antigens). These antibodies bind to the graft endothelium, activating the complement system and leading to immediate thrombosis, fibrinoid necrosis, and graft failure [1]. **Analysis of Options:** * **Option A (12 hours):** This is the correct timeframe. Hyperacute rejection is immediate; if it occurs, it is usually evident before the patient leaves the operating table or within the first few hours post-surgery. * **Option B (2 weeks):** This timeframe is characteristic of **Acute Rejection**, which typically occurs within days to weeks (usually within the first 6 months) [1]. It is primarily T-cell mediated (Type IV hypersensitivity). * **Option C & D (1 month & 3 months):** These timeframes fall under the spectrum of Acute or **Chronic Rejection**. Chronic rejection occurs months to years after transplantation and involves slow, progressive fibrosis and vascular occlusion (e.g., Graft Arteriosclerosis). **High-Yield NEET-PG Pearls:** 1. **Mechanism:** Pre-formed antibodies → Complement activation → Thrombosis [1]. 2. **Gross Appearance:** The graft becomes cyanotic, mottled, and flaccid (often called a "blue kidney") [1]. 3. **Prevention:** It is prevented by **Cross-matching** (testing recipient serum against donor lymphocytes) and ABO typing. 4. **Treatment:** There is no effective treatment once it begins; the graft must be surgically removed [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 241-242.

Q: What is the HLA marker associated with Behcet's syndrome?

HLA-B51. **Explanation:** **HLA-B51** is the strongest genetic risk factor associated with **Behcet’s Syndrome**, a multi-systemic inflammatory disorder characterized by the triad of recurrent oral ulcers, genital ulcers, and uveitis. While the exact pathogenesis is unknown, it is considered an autoinflammatory vasculitis where HLA-B51 plays a role in neutrophil hyper-reactivity. **Analysis of Options:** * **HLA-B27 (Option A):** This is the classic marker for **Seronegative Spondyloarthropathies**, including Ankylosing Spondylitis (strongest association), Reiter’s syndrome (Reactive arthritis), Psoriatic arthritis, and Enteropathic arthritis [1]. * **HLA-DR5 (Option B):** This marker is primarily associated with **Hashimoto’s thyroiditis** and sometimes Kaposi sarcoma. (Note: HLA-DR3 and DR4 are more commonly tested for autoimmune conditions like SLE and Rheumatoid Arthritis). * **HLA-Cw6 (Option D):** This is strongly linked to **Psoriasis vulgaris**, particularly early-onset (Type I) psoriasis. **High-Yield Clinical Pearls for NEET-PG:** * **Behcet’s Syndrome Triad:** Oral ulcers (most common), Genital ulcers (most specific), and Uveitis. * **Pathergy Test:** A unique diagnostic feature where a minor skin prick leads to the formation of a sterile pustule or papule within 48 hours. * **Geographic Distribution:** Highest prevalence is found along the **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 49-50.

Question 1

Acute graft versus host disease reaction occurs in all EXCEPT?

Accepted Answer

Adrenal

Answer

Liver

Answer

Gut

Answer

Skin

Question 2

Which cell type is primarily involved in immunity against parasitic infections?

Accepted Answer

Eosinophil

Answer

Neutrophil

Answer

Basophil

Answer

Lymphocyte

Question 3

Which of the following is NOT true about angioneurotic edema?

Accepted Answer

Pitting edema of face, lips, and mucous membranes

Answer

Can be caused by CI esterase inhibitor deficiency

Answer

Can be provoked by extreme temperature exposure

Answer

Is known to be associated with ACE inhibitors

Question 4

Hyperacute rejection occurs within:

Accepted Answer

12 hours

Answer

2 weeks

Answer

1 month

Answer

3 months

Question 5

Which antibody is found in myositis?

Accepted Answer

Anti-Jo-1

Answer

Anti-Scl-70

Answer

Anti-Sm

Answer

Anti-Ku

Question 6

Plasma cells are activated by which of the following cell types?

Accepted Answer

B cells

Answer

T cells

Answer

Macrophages

Answer

Monocytes

Question 7

An 18-year-old man is evaluated for possible immunodeficiency disease due to a lifelong history of chronic lung infections, recurrent otitis media, and multiple episodes of bacterial meningitis. Although total IgG is normal, the patient has a selective deficiency of IgG2. An associated deficiency of which of the following other substances may produce anaphylaxis when blood products are given to such individuals?

Accepted Answer

IgA

Answer

C3

Answer

C4

Answer

IgE

Question 8

What is the HLA marker associated with Behcet's syndrome?

Accepted Answer

HLA-B51

Answer

HLA-B27

Answer

HLA-DR5

Answer

HLA-CW6

Question 9

Which of the following conditions is associated with ANCA?

Accepted Answer

Wegener’s granulomatosis

Answer

Henoch-Schonlein Purpura

Answer

Rheumatoid arthritis

Answer

Goodpasture syndrome

Question 10

Acute graft rejection typically occurs within what timeframe?

Accepted Answer

3 months

Answer

3 hours

Answer

3 days

Answer

3 years

Immunopathology — MCQs

Immunopathology — MCQs

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