Transplantation Immunopathology — MCQs
Which of the following drugs shows nephrotoxicity during administration?
Acute graft rejection occurs within?
What is the primary mechanism responsible for skin graft survival within the first 48 hours after transplantation?
What is the most common immunosuppressant regimen used in renal transplant for maintenance?
If mother is donating the kidney to her son, this is an example of:-
The hypersensitivity reaction involved in the hyperacute rejection of a renal transplant is:
What is the consequence of preformed antibodies in organ transplantation?
A dentist suffered from Hepatitis B infection 3 months back. His liver function tests are normal, but HBsAg remains positive and he is not allowed by the medical board to do surgical practice. He is:
A dentist who got infected with Hepatitis B has recovered from it for the last 3 months. His laboratory tests are normal, but he is not allowed to treat patients. He is known as?
What is the Rose Waaler test used for?
Transplantation Immunopathology Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following drugs shows nephrotoxicity during administration?
- A. Azathioprine
- B. Tacrolimus (Correct Answer)
- C. Mycophenolate mofetil
- D. Leflunomide
Explanation: ***Tacrolimus*** - **Tacrolimus** is a calcineurin inhibitor and a well-known cause of **nephrotoxicity**, which can manifest as acute kidney injury or chronic renal dysfunction [1], [4]. - Its mechanism involves vasoconstriction of afferent arterioles and direct tubular toxicity, leading to reduced glomerular filtration. *Azathioprine* - **Azathioprine** is an immunosuppressant primarily associated with **bone marrow suppression** (leukopenia, thrombocytopenia) and **hepatotoxicity**, not typically nephrotoxicity [2]. - While it can cause renal impairment in rare cases, it is not a primary mechanism of action. *Mycophenolate mofetil* - **Mycophenolate mofetil (MMF)** is an immunosuppressant that primarily causes **gastrointestinal side effects** (diarrhea, nausea) and **myelosuppression**. - It is generally considered **renal-sparing** and is often used in situations where calcineurin inhibitors are contraindicated due to nephrotoxicity. *Leflunomide* - **Leflunomide** is an immunosuppressant used in rheumatoid arthritis, known for causing **hepatotoxicity**, **hypertension**, and **teratogenicity** [3]. - While it can affect various organ systems, direct and significant nephrotoxicity is not a prominent adverse effect.
Question 2: Acute graft rejection occurs within?
- A. Few minutes
- B. 6-12 months
- C. Few hours
- D. < 6 months (Correct Answer)
Explanation: ***< 6 months*** - **Acute graft rejection** typically occurs within the first few **weeks to months** after transplantation due to a T-cell mediated immune response against the donor organ [1]. - While it can manifest at any time, the majority of cases occur within the **first 6 months** post-transplant, making this the most appropriate time frame [1]. *Few minutes* - Rejection presenting within minutes of transplantation is characteristic of **hyperacute rejection**, which is caused by pre-existing **donor-specific antibodies** [1]. - This rapid form of rejection is mediated by **complement activation** and leads to immediate graft failure [1]. *6-12 months* - Rejection occurring in this timeframe might still be acute, but the peak incidence is generally earlier. - Rejection presenting after 6 months is often categorized as **late acute rejection** or may start to transition towards signs of chronic rejection, which occurs over a longer period. *Few hours* - Rejection within a few hours could be a very early form of **acute rejection** or a delayed presentation of **hyperacute rejection** [1]. - However, the classic presentation of acute rejection is more prolonged than a few hours, usually developing over days to weeks. **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 3: What is the primary mechanism responsible for skin graft survival within the first 48 hours after transplantation?
- A. Amount of saline in graft
- B. Plasma imbibition (Correct Answer)
- C. New vessels growing from the donor tissue
- D. Connection between donor and recipient capillaries
Explanation: ***Correct: Plasma imbibition*** - **Plasma imbibition** is the initial process where the transplanted graft absorbs nutrients and oxygen from the recipient bed through diffusion. - This fluid uptake is crucial for the survival of the graft cells before revascularization occurs, typically within the first **24-48 hours**. - The graft acts like a sponge, absorbing serum and plasma from the vascular bed through capillary action and osmosis. *Incorrect: Amount of saline in graft* - While sterile saline is often used to keep donor tissue moist during harvesting and transport, its presence in the graft itself is not the primary mechanism for survival post-transplantation. - Excessive saline could even lead to **edema** and compromise graft take if not properly drained or if it prevents good contact with the recipient bed. *Incorrect: New vessels growing from the donor tissue* - Grafts themselves do not spontaneously grow new vessels; new blood vessels are formed by **angiogenesis** from the recipient bed into the graft over several days. - This process, called **inosculation** and subsequent neovascularization, provides long-term blood supply but is not the primary mechanism of survival within the *first 48 hours*. *Incorrect: Connection between donor and recipient capillaries* - The direct connection of donor and recipient capillaries (inosculation) is a later stage of graft vascularization, typically beginning after **3-5 days**, not within the first 48 hours. - Within the initial 48 hours, the graft relies on diffusion because a complete vascular connection has not yet been established.
Question 4: What is the most common immunosuppressant regimen used in renal transplant for maintenance?
- A. Calcineurin inhibitors + Purine antagonists + Basliximab
- B. Glucocorticoids + Cyclophosphamide
- C. Cyclophosphamide + Purine antagonists + Glucocorticoids
- D. Calcineurin inhibitors + Purine antagonists + Glucocorticoids (Correct Answer)
Explanation: ***Calcineurin inhibitors + Purine antagonists + Glucocorticoids*** - This triple therapy regimen is the **most common and effective** approach for long-term maintenance immunosuppression in renal transplant recipients [1]. - **Calcineurin inhibitors** (e.g., tacrolimus, cyclosporine) are the cornerstone for preventing T-cell activation, **purine antagonists** (e.g., mycophenolate mofetil, azathioprine) inhibit lymphocyte proliferation, and **glucocorticoids** provide broad anti-inflammatory effects [1]. *Calcineurin inhibitors + Purine antagonists + Basliximab* - **Basiliximab** is typically used for **induction therapy** (immediately post-transplant) to prevent acute rejection by blocking the IL-2 receptor, not as a long-term maintenance component. - The standard maintenance regimen *replaces* induction agents like basiliximab with a long-term steroid or calcineurin inhibitor alongside a purine antagonist. *Glucocorticoids + Cyclophosphamide* - **Cyclophosphamide** is a potent alkylating agent primarily used in specific autoimmune diseases or certain cancers, and its use in transplant is generally limited to cases of organ rejection resistant to standard therapy due to its significant toxicity. - This combination is **not a standard maintenance regimen** for renal transplant due to the high toxicity and side effects of cyclophosphamide. *Cyclophosphamide + Purine antagonists + Glucocorticoids* - As mentioned, **cyclophosphamide** is not a first-line agent for maintenance immunosuppression in renal transplant due to its severe side effect profile, including myelosuppression and hemorrhagic cystitis. - While purine antagonists and glucocorticoids are components of maintenance therapy, the inclusion of cyclophosphamide makes this an **uncommon and usually unfavorable regimen** for long-term use.
Question 5: If mother is donating the kidney to her son, this is an example of:-
- A. Autograft
- B. Allograft (Correct Answer)
- C. Isograft
- D. Xenograft
Explanation: ***Correct: Allograft*** - An **allograft** involves the transplantation of organs or tissues between **genetically different individuals of the same species** - In this scenario, a mother donating a kidney to her son is a classic example, as they are genetically distinct (share approximately 50% DNA) but belong to the same human species - This is the **most common type of transplant** performed in clinical practice *Incorrect: Autograft* - An **autograft** involves transplanting tissues or organs from one part of the body to another in the **same individual** - Examples include skin grafts from a patient's thigh to an injured area on their arm, or using saphenous vein for coronary artery bypass grafting - This does not apply to mother-son transplantation as two different individuals are involved *Incorrect: Isograft* - An **isograft** refers to a transplant between **genetically identical individuals**, such as monozygotic (identical) twins - The mother and son are not genetically identical (they share only ~50% of their DNA), thus precluding an isograft - Isografts have minimal risk of rejection due to genetic identity *Incorrect: Xenograft* - A **xenograft** is a transplant of organs or tissues **from one species to another** - Examples include transplanting a pig heart valve into a human or using bovine pericardium - Mother and son are both humans (same species), so this is not a xenograft
Question 6: The hypersensitivity reaction involved in the hyperacute rejection of a renal transplant is:
- A. Type I
- B. Type III
- C. Type IV
- D. Type II (Correct Answer)
Explanation: ***Type II*** - Hyperacute rejection is primarily mediated by **antibody-mediated mechanisms**, indicative of Type II hypersensitivity [2]. - It involves pre-existing **IgG antibodies** that react against donor renal graft antigen, leading to rapid graft destruction [1]. *Type I* - Type I hypersensitivity is associated with **allergic reactions** involving **IgE antibodies**, not relevant to transplant rejection [2]. - Typically involves conditions like **anaphylaxis** or **asthma**, which are unrelated to hyperacute rejection scenarios. *Type IV* - Type IV hypersensitivity is cell-mediated and typically manifests as **delayed-type hypersensitivity**, not acute rejection. - It involves **T cells** and does not play a role in the immediate immune response seen in hyperacute rejection. *Type III* - Type III hypersensitivity involves the formation of immune complexes, leading to conditions like **serum sickness**, not hyperacute rejection. - This type of reaction is usually more relevant in **chronic inflammatory conditions** rather than immediate transplant rejections. **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. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 208-210.
Question 7: What is the consequence of preformed antibodies in organ transplantation?
- A. Delayed T-cell mediated rejection
- B. Long-term graft dysfunction due to chronic inflammation
- C. Post-transplant antibody-mediated rejection
- D. Immediate graft failure due to preformed antibodies (Correct Answer)
Explanation: ***Hyperacute rejection*** - This occurs immediately after transplant due to **preformed antibodies** reacting against donor antigens, leading to rapid allograft failure [1]. - It is typically associated with **complement activation** and often results in thrombosis of the graft vessels [1]. *Acute rejection* - Primarily mediated by **T cells** rather than preformed antibodies, occurring days to months after transplantation [2]. - Involves a **cellular immune response**, unlike hyperacute rejection which is antibody-mediated [2]. *Acute humoral rejection* - Also involves antibodies but develops **days to weeks** post-transplant rather than immediately like hyperacute rejection. - This type is characterized by a **specific antibody response** and complement activation, but is not due to preformed antibodies. *Chronic rejection* - A long-term process that develops over months to years due to **persistent immune-mediated injury** to the graft, leading to gradual loss of function. - Involves mechanisms such as **tissue fibrosis and vascular changes**, differing from the immediate action of preformed antibodies in hyperacute rejection. **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. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 242.
Question 8: A dentist suffered from Hepatitis B infection 3 months back. His liver function tests are normal, but HBsAg remains positive and he is not allowed by the medical board to do surgical practice. He is:
- A. Inactive carrier
- B. Healthy carrier (Correct Answer)
- C. Convalescent carrier
- D. Paradoxical carrier
Explanation: ***Healthy carrier*** - A **healthy carrier** is an asymptomatic individual who harbors and can transmit the infectious agent while appearing clinically well with **normal liver function tests**. - The dentist has **recovered clinically** (normal LFTs) but remains **HBsAg positive at 3 months**, making him infectious and capable of transmitting hepatitis B to patients during exposure-prone procedures. - This is the **appropriate classification** for someone who is asymptomatic with persistent HBsAg beyond the acute phase but before the 6-month mark that defines chronic infection. - The **practice restriction** is justified because healthy carriers pose a **transmission risk** in surgical and dental procedures involving blood exposure. *Inactive carrier* - An **inactive carrier** (or inactive chronic HBsAg carrier) is a more specific term for individuals with **chronic HBV infection** (HBsAg positive >6 months) who have minimal viral replication, normal ALT, and low/undetectable HBV DNA. - At **3 months post-infection**, chronic carrier state cannot yet be definitively diagnosed as chronicity requires **persistence beyond 6 months**. - While this patient may eventually become an inactive carrier, at 3 months the broader term "healthy carrier" is more appropriate. *Convalescent carrier* - A **convalescent carrier** harbors and sheds pathogens during the **immediate recovery phase** of acute illness, typically for **days to a few weeks**. - At **3 months post-infection**, the patient is well beyond the convalescent period and has entered a **persistent carrier state** rather than active convalescence. - This term is too time-limited to accurately describe someone with **persistent HBsAg at 3 months**. *Paradoxical carrier* - The term **paradoxical carrier** is **not a recognized classification** in hepatitis B epidemiology or standard infectious disease carrier state terminology. - It does not appear in authoritative texts on **viral hepatitis** or carrier state definitions.
Question 9: A dentist who got infected with Hepatitis B has recovered from it for the last 3 months. His laboratory tests are normal, but he is not allowed to treat patients. He is known as?
- A. Chronic carrier
- B. Convalescent carrier (Correct Answer)
- C. Active carrier
- D. Paradoxical carrier
Explanation: ***Convalescent carrier*** - A **convalescent carrier** is someone who has recovered clinically from an acute infection but continues to harbor and can transmit the pathogen during the recovery period, typically for **weeks to a few months** after apparent recovery. - In Hepatitis B, a convalescent carrier may still have **HBsAg positivity** despite normal liver function tests and clinical recovery, and can transmit the virus during this period. - The scenario describes a dentist who recovered **3 months ago** with normal laboratory tests but is still restricted from treating patients, indicating he remains in the **convalescent carrier phase** and has not yet reached the 6-month threshold for chronic carrier status. - This is why healthcare workers in this phase are temporarily restricted from exposure-prone procedures to prevent transmission. *Chronic carrier* - A **chronic carrier** state for Hepatitis B is defined by the persistence of **HBsAg** (Hepatitis B surface antigen) for **more than 6 months** after acute infection. - While chronic carriers can have normal liver function tests, the key distinguishing feature is the **duration >6 months**, which does not match the **3-month timeline** described in this question. - The dentist has not yet met the temporal criterion for chronic carrier classification. *Active carrier* - The term **active carrier** is not a standard epidemiological classification in medical literature and lacks precise definition. - While both convalescent and chronic carriers can actively transmit disease, the term "active" does not specify the **phase or duration** of the carrier state, which is critical for classification. *Paradoxical carrier* - There is no recognized medical definition for **paradoxical carrier** in epidemiology or infectious disease literature. - This is a distracter with no clinical relevance to carrier state classification.
Question 10: What is the Rose Waaler test used for?
- A. Ring precipitation
- B. Precipitation in gel
- C. Complement fixation test
- D. Passive hemagglutination test (Correct Answer)
Explanation: ***Passive hemagglutination test*** - The **Rose Waaler test** is a historical **rheumatoid factor (RF)** detection method based on **passive hemagglutination**. - It uses sheep red blood cells coated with a subagglutinating dose of rabbit anti-sheep red blood cell antibody to detect RF in patient serum. *Complement fixation test* - This assay detects the presence of **antibody** or **antigen** by observing whether **complement** is consumed in an antigen-antibody reaction. - The Rose Waaler test does not involve the measurement of complement consumption. *Precipitation in gel* - This technique, such as **immunodiffusion**, involves the formation of a visible **precipitate** when soluble antigens and antibodies diffuse through a gel matrix and meet at optimal concentrations. - The Rose Waaler test relies on agglutination of red blood cells, not precipitation in gel. *Ring precipitation* - A **ring precipitation test** involves layering an antigen solution over an antibody solution, creating an antigen-antibody complex visible as a **precipitate ring** at the interface of the two solutions. - This method is distinct from the Rose Waaler test which uses red blood cell agglutination.
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