Immunopathology Practice Questions

Q: Amyloidosis is associated with all of the following conditions except?

Chronic bronchitis. ***Chronic bronchitis*** - Chronic bronchitis is primarily characterized by **inflammation of the airways** and **excess mucus production**, not typically associated with amyloidosis [1]. - Amyloidosis more commonly relates to chronic inflammatory states but does not directly result from the long-term exposure seen in chronic bronchitis [1]. *Tuberculosis* - Tuberculosis can lead to chronic inflammation, which may precipitate **secondary amyloidosis** due to persistent infection [1]. - It often causes systemic effects, including weight loss and fever, which can result in **amyloid deposition** [1]. *Osteomyelitis* - Osteomyelitis, as a chronic bone infection, can trigger an inflammatory response leading to **secondary amyloidosis** [1]. - The ongoing inflammation can result in the accumulation of amyloid proteins in the bone and surrounding tissues [1]. *Bronchiectasis* - Bronchiectasis often results from persistent lung infections leading to chronic inflammation, which can cause **amyloid deposition** [1,3]. - It is associated with recurrent lung infections and can lead to systemic complications, including amyloidosis [1,3]. **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. 135-136. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 269-270.

Q: HLA is located on ?

Short arm of chr-6. ***Short arm of chr-6*** - The **Human Leukocyte Antigen (HLA)** complex, crucial for immune recognition, is located on the **short arm of chromosome 6**. [1] - This region, specifically 6p21.3, contains highly polymorphic genes encoding MHC (Major Histocompatibility Complex) proteins. [2] *Long arm of chr-6* - The **long arm of chromosome 6** contains many genes, but the primary HLA complex is not located here. - Genes on the long arm are involved in various cellular functions, but not central to immune recognition via HLA. *Short arm of chr-3* - Genes on **chromosome 3**, including its short arm, are not associated with the primary HLA complex. - Chromosome 3 is known for genes related to conditions such as von Hippel-Lindau disease. *Long arm of chr-3* - The **long arm of chromosome 3** is not the location for the HLA complex. - This region contains genes involved in diverse cellular processes and disease associations, but not immune recognition via HLA molecules. **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. 55-56. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 239-240.

Q: What color is emitted by FITC after absorbing blue light?

Yellow-green. ***Yellow-green*** - Fluorescein isothiocyanate (FITC) is a common fluorochrome used in **fluorescence microscopy** and flow cytometry. - Upon excitation by blue light (typically around 495 nm), FITC emits light in the **yellow-green spectrum**, specifically around 521 nm. - This is the **spectroscopically accurate** description of FITC's emission peak. *Orange-red* - **Orange-red emission** is characteristic of fluorochromes like **phycoerythrin (PE)** or **Texas Red**, not FITC. - These fluorochromes have different **excitation and emission maxima** compared to FITC. *Apple-green* - While FITC fluorescence is sometimes clinically described as **"apple-green"** (especially in immunofluorescence), this is a **subjective visual description** rather than a precise spectral term. - The more **spectroscopically accurate** description is **yellow-green**, which reflects FITC's specific emission peak at 521 nm. - "Apple-green" typically suggests a purer green without the yellow component. *Golden-brown* - **Golden-brown** is not a typical emission color for fluorochromes like FITC. - This color is generally associated with **pigments** or stained tissues (e.g., lipofuscin, hemosiderin), not fluorescent probes.

Q: What laboratory findings are associated with common variable hypogammaglobulinemia?

Low serum immunoglobulin levels. ***Low serum immunoglobulin levels*** - **Common variable hypogammaglobulinemia (CVID)** is characterized by significantly **low levels of IgG, IgA, and/or IgM** due to impaired B cell differentiation into plasma cells. - This deficiency in antibodies is the hallmark of the disorder, explaining the increased susceptibility to infections. *Decreased B cell count* - While CVID involves impaired B cell function, the **B cell counts** in the peripheral blood are typically **normal** or sometimes even elevated [1]. - The problem lies in their inability to differentiate and produce adequate antibodies, not in their numerical presence [1]. *Increased B cell count* - An increased B cell count is not a characteristic finding in CVID; peripheral B cell numbers are usually normal [1]. - If B cell counts are significantly increased, other conditions such as certain **lymphoproliferative disorders** should be considered. *Neutropenia* - **Neutropenia** (low neutrophil count) is not a primary diagnostic feature of CVID, although it can occur in some patients with autoimmune complications. - The defining laboratory finding is the **deficiency of immunoglobulins**, leading to recurrent infections. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 249-250.

Q: A mutation in the transthyretin (TTR) protein causes which of the following types of amyloidosis?

Familial amyloidotic polyneuropathy. ***Familial amyloidotic polyneuropathy*** - This condition is specifically caused by **mutations in the transthyretin (TTR) protein**, leading to amyloid deposition primarily in nerves [1]. - It presents with **peripheral neuropathy**, including sensory and autonomic symptoms, which align with TTR mutations [1]. *Familial Mediterranean fever* - This is an autoinflammatory disorder caused by mutations in the **MEFV gene**, unrelated to transthyretin. - It is characterized by recurrent **fever, abdominal pain**, and **serositis**, not amyloidosis caused by TTR. *Prion protein associated amyloidosis* - Relates to prion diseases like **Creutzfeldt-Jakob disease**, caused by abnormal **prion proteins** rather than TTR [1]. - Symptoms are usually **neurodegenerative** in nature, not linked to familial amyloidogenic processes. *Dialysis associated amyloidosis* - This form of amyloidosis is due to the accumulation of **beta-2 microglobulin**, not mutations in TTR [1]. - Commonly presents with **joint pain** and carpal tunnel syndrome associated with long-term dialysis [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, p. 266.

Q: Which of the following best explains the development of intravascular hemolysis in a 54-year-old woman who was given type A Rh+ blood by mistake, despite being a type B Rh+ patient, after a blood transfusion following an automobile accident?

Antibody-mediated complement fixation. ***Antibody-mediated complement fixation*** - Intravascular hemolysis occurs when type B blood is transfused with type A blood, triggering **IgM antibodies** to activate **complement**, leading to the destruction of transfused red blood cells [1][2]. - This mechanism is rapid and results in **hemolytic transfusion reactions**, which are life-threatening and present shortly after the transfusion [1]. *Antibody-dependent cellular cytotoxicity* - This process primarily involves **IgG antibodies** targeting cells for destruction by **NK cells** or macrophages, rather than complement activation. - It usually leads to **extravascular hemolysis** rather than intravascular hemolysis caused by complement. *Delayed-type hypersensitivity* - This immune response is mediated by **T cells** and typically occurs days to weeks after exposure, not immediately as seen in transfusion reactions. - It does not directly lead to **hemolysis** but rather to tissue damage due to cellular immunity. *Immune complex disease* - Characterized by **formation of immune complexes** leading to inflammation and sometimes tissue damage, but not specifically linked to immediate hemolytic reactions. - This mechanism is more relevant in conditions like **serum sickness**, rather than the direct hemolysis observed in this transfusion scenario. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Red Blood Cell and Bleeding Disorders, pp. 673-674. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 627-628.

Q: Defective phagolysosome formation is a feature of which condition?

Chediak-Higashi syndrome. ***Chediak-Higashi syndrome*** - This condition is characterized by **defective phagolysosome formation** due to mutations in the LYST gene, leading to impaired killing of pathogens [1]. - Clinical features include **partial oculocutaneous albinism** and **neurological deficits**, along with recurrent infections [1]. *Chronic granulomatous disease* - It primarily involves a defect in the **NADPH oxidase enzyme**, leading to ineffective respiratory burst and inability to kill certain bacteria. - Patients experience recurrent infections from **catalase-positive organisms**, not primarily due to phagolysosome defects. *Ataxia telangiectasia* - This is an inherited disorder affecting DNA repair mechanisms and results in **neurological issues** and **immunodeficiency** but not specifically phagolysosome dysfunction. - Common features include **ataxia**, **telangiectasias**, and an increased risk of malignancies, rather than recurrent infections from phagocyte defects. *Fanconi Anemia* - This condition is associated with **bone marrow failure** and increased susceptibility to cancer, particularly **acute myeloid leukemia**, rather than phagolysosomal dysfunction. - Clinically, it presents with **hypoplastic anemia**, **short stature**, and **skeletal anomalies**, not recurrent infections due to impaired phagolysosome function. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 245-246.

Question 1

Amyloidosis is associated with all of the following conditions except?

Accepted Answer

Chronic bronchitis

Answer

Osteomyelitis

Answer

Bronchiectasis

Answer

Tuberculosis

Question 2

HLA is located on ?

Accepted Answer

Short arm of chr-6

Answer

Long arm of chr-6

Answer

Short arm of chr-3

Answer

Long arm of chr-3

Question 3

What color is emitted by FITC after absorbing blue light?

Accepted Answer

Yellow-green

Answer

Orange-red

Answer

Apple-green

Answer

Golden-brown

Question 4

What laboratory findings are associated with common variable hypogammaglobulinemia?

Accepted Answer

Low serum immunoglobulin levels

Answer

Decreased B cell count

Answer

Increased B cell count

Answer

Neutropenia

Question 5

A mutation in the transthyretin (TTR) protein causes which of the following types of amyloidosis?

Accepted Answer

Familial amyloidotic polyneuropathy

Answer

Familial Mediterranean fever

Answer

Dialysis associated amyloidosis

Answer

Prion protein associated amyloidosis

Question 6

A 6-month-old male infant presents with recurrent severe bacterial infections with encapsulated organisms (Streptococcus pneumoniae and Haemophilus influenzae). Laboratory findings reveal profound deficiency of all immunoglobulin classes (IgG, IgA, IgM) with absent mature B cells in peripheral blood. The most likely diagnosis is:

Accepted Answer

X-linked agammaglobulinemia of Bruton

Answer

DiGeorge's syndrome

Answer

Isolated IgA deficiency

Answer

Chronic granulomatous disease

Question 7

Which among the following is an example of type I hypersensitivity reaction?

Accepted Answer

Casoni's test

Answer

Graves' disease

Answer

Pernicious anemia

Answer

Arthus reaction

Question 8

Which of the following best explains the development of intravascular hemolysis in a 54-year-old woman who was given type A Rh+ blood by mistake, despite being a type B Rh+ patient, after a blood transfusion following an automobile accident?

Accepted Answer

Antibody-mediated complement fixation

Answer

Direct cytotoxic T-cell mediated lysis

Answer

Immune complex mediated hemolysis

Answer

Antibody-dependent cellular cytotoxicity

Question 9

Defective phagolysosome formation is a feature of which condition?

Accepted Answer

Chediak-Higashi syndrome

Answer

Fanconi Anemia

Answer

Ataxia telangiectasia

Answer

Chronic granulomatous disease

Question 10

All of the following are pattern recognition receptors for extracellular or ingested microbes, except:

Accepted Answer

Killer-cell immunoglobulin receptors (KIRs) - Recognize MHC class I molecules on host cells.

Answer

Toll-like receptors (TLRs) - Detect pathogen-associated molecular patterns (PAMPs).

Answer

NOD-like receptors (NLRs) - Intracellular sensors for microbial components.

Answer

C-type lectin receptors (CLRs) - Recognize carbohydrate structures on microbes.

Immunopathology — MCQs

Immunopathology — MCQs

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