Immunopathology Practice Questions

Q: Hyperacute rejection occurs within which timeframe?

12 hours. **Explanation:** **Hyperacute rejection** is a Type II hypersensitivity reaction mediated by **preformed antibodies** (IgG) in the recipient’s serum against the donor’s antigens (typically ABO blood group or HLA antigens). 1. **Why 12 hours is correct:** Hyperacute rejection occurs almost immediately—ranging from **minutes to a few hours** after the graft is vascularized [1]. Because the antibodies are already present, they immediately bind to the vascular endothelium of the graft, triggering the complement cascade, thrombosis, and fibrinoid necrosis [1]. In the context of the options provided, **12 hours** is the most accurate timeframe representing this immediate post-surgical window. 2. **Why the other options are incorrect:** * **2 weeks:** This timeframe is characteristic of **Acute Rejection**. Acute rejection is T-cell mediated (Type IV) or antibody-mediated (Type II) and typically occurs within days to a few weeks (usually <6 months) as the recipient's immune system takes time to recognize and respond to the new antigens [1]. * **1 month & 3 months:** These periods fall under the spectrum of **Acute Rejection** or the beginning of **Chronic Rejection**. Chronic rejection occurs over months to years and is characterized by intimal thickening and fibrosis (arteriosclerosis). **High-Yield NEET-PG Pearls:** * **Mechanism:** Preformed antibodies → Complement activation → Endothelial damage → **Thrombosis and Fibrinoid Necrosis** [1]. * **Gross Appearance:** The kidney rapidly becomes cyanotic, mottled, and flaccid (often described as a "blue kidney") [1]. * **Prevention:** Mandatory **Cross-matching** (mixing recipient serum with donor lymphocytes) before transplantation has made hyperacute rejection rare in modern clinical practice. **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.

Question 1

Which pair of organs is involved in Goodpasture's syndrome?

Accepted Answer

Kidney and lungs

Answer

Kidney and intestine

Answer

Kidney and heart

Answer

Kidney and liver

Question 2

Sago spleen is seen in which condition?

Accepted Answer

Amyloidosis

Answer

Infarction

Answer

Chronic venous congestion

Answer

Tuberculosis

Question 3

Which marker is characteristic of Natural Killer (NK) cells?

Accepted Answer

CD 56

Answer

CD 34

Answer

CD 1

Answer

CD 45

Question 4

Granuloma formation is seen in which type of hypersensitivity reaction?

Accepted Answer

Type IV

Answer

Type I

Answer

Type II

Answer

Type III

Question 5

Which of the following cell types is most commonly associated with chronic allergic asthma?

Accepted Answer

TH2

Answer

TH17

Answer

TH1

Answer

TH4

Question 6

All of the following are included in the Sydney revision of the Sapporo criteria for Antiphospholipid antibody syndrome EXCEPT:

Accepted Answer

Livedo reticularis

Answer

Vascular thrombosis

Answer

3 or more unexplained spontaneous abortions

Answer

Lupus anticoagulant in plasma

Question 7

Human immunodeficiency virus (HIV) affects the immune response. What is the primary change it brings about?

Accepted Answer

Defect in cell-mediated immunity

Answer

A gammaglobulinemia

Answer

Defect in complement system

Answer

Defect in natural killer cells

Question 8

C5a acts as a/an?

Accepted Answer

Chemotactic agent

Answer

Opsonin

Answer

Membrane Attack Complex (MAC)

Answer

Vasodilator

Question 9

A patient presented with generalized edema, sweating, flushing, tachycardia, and fever after a bee sting. What type of hypersensitivity reaction is this?

Accepted Answer

IgE mediated reaction

Answer

T cell mediated cytotoxicity

Answer

IgG mediated reaction

Answer

IgA mediated hypersensitivity reaction

Question 10

Hyperacute rejection occurs within which timeframe?

Accepted Answer

12 hours

Answer

2 weeks

Answer

1 month

Answer

3 months

Immunopathology — MCQs

Immunopathology — MCQs

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