Immunopathology Practice Questions

Q: Primary mediators of anaphylaxis are all EXCEPT:

TNF. **Explanation:** The question tests the distinction between **preformed (primary)** and **newly synthesized (secondary)** mediators released during Type I Hypersensitivity (Anaphylaxis). **Why TNF is the Correct Answer:** Tumor Necrosis Factor (TNF) is classified as a **secondary mediator** (specifically a cytokine) [1]. While mast cells do store some preformed TNF, the bulk of TNF involved in systemic inflammatory responses is synthesized and secreted *de novo* after mast cell activation. It plays a major role in the late-phase reaction by promoting leukocyte recruitment, rather than the immediate vascular changes seen in acute anaphylaxis [1]. **Analysis of Incorrect Options:** * **Histamine (Option A):** The most important **primary mediator**. It is preformed and stored in mast cell granules [3]. Upon degranulation, it causes immediate vasodilation, increased vascular permeability, and bronchial smooth muscle contraction [2]. * **Serotonin (Option B):** A **primary mediator** stored in the granules of mast cells (especially in rodents) and platelets [3]. It acts as a potent vasoconstrictor and increases vascular permeability [2]. * **Prostaglandins (Option C):** While often categorized as **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 211-212. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 101. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 93-94.

Q: Which of the following cytokines is secreted by classically activated macrophages (M1)?

IL-1. **Explanation:** Macrophages can be activated via two distinct pathways: the **Classical (M1)** pathway and the **Alternative (M2)** pathway [1]. **1. Why IL-1 is correct:** Classically activated macrophages (M1) are induced by microbial products (like LPS) and IFN-γ [1]. Once activated, M1 macrophages function as "pro-inflammatory" cells. They secrete potent inflammatory cytokines, primarily **IL-1, IL-12, IL-23, and TNF** [1]. These cytokines serve to recruit more leukocytes and initiate the acute inflammatory response. M1 cells also produce reactive oxygen species (ROS) and nitric oxide (NO) to facilitate microbicidal activity [1]. **2. Why the other options are incorrect:** * **IL-2:** This is a T-cell growth factor primarily secreted by **Th1 cells**, not macrophages. It stimulates the proliferation of T-lymphocytes and NK cells. * **IL-4:** This is the hallmark cytokine of the **Th2 response**. It actually inhibits M1 activation and instead promotes **Alternative (M2) macrophage activation**, which is involved in tissue repair and anti-inflammatory responses [1]. * **IL-3:** This is a hematopoietic growth factor secreted by activated T-cells that stimulates the production of cells in the bone marrow. **High-Yield Clinical Pearls for NEET-PG:** * **M1 (Classical):** Induced by IFN-γ; Pro-inflammatory; Secretes **IL-1, IL-12, TNF**; Involved in inflammation and tissue destruction [1]. * **M2 (Alternative):** Induced by **IL-4, IL-13**; Anti-inflammatory; Secretes **IL-10, TGF-β**; Involved in tissue repair, fibrosis, and wound healing [1]. * **Memory Aid:** **M1** = "Murder" (Microbicidal/Inflammation); **M2** = "Mend" (Repair/Healing). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 104-107.

Question 1

The immune system in asthmatics is typically skewed towards which of the following phenotypes?

Accepted Answer

Th2 phenotype

Answer

Th1 phenotype

Answer

Th3 phenotype

Answer

Th0 phenotype

Question 2

What are the most important cells acting against virus-infected cells and cancer cells?

Accepted Answer

Natural killer cells

Answer

Neutrophils

Answer

Basophils

Answer

Langerhans cells

Question 3

Nude mice are able to accept xenografts because they lack which type of immune cell?

Accepted Answer

T cells

Answer

B cells

Answer

NK cells

Answer

LAK cells

Question 4

All of the following statements about Ataxia-Telangiectasia are true, except?

Accepted Answer

Selective absence of IgM

Answer

Autosomal Recessive disorder

Answer

Lymphoreticular malignancy

Answer

Progressive Cerebellar ataxia

Question 5

Which of the following conditions represents a type 3 hypersensitivity reaction (immune complex disease)?

Accepted Answer

Systemic Lupus Erythematosus (SLE)

Answer

Diabetes Mellitus Type I

Answer

Goodpasture syndrome

Answer

Multiple sclerosis

Question 6

Antibodies against double-stranded DNA and smooth muscle antigens are virtually diagnostic of which condition?

Accepted Answer

Systemic Lupus Erythematosus

Answer

Systemic sclerosis

Answer

Sjogren's disease

Answer

Wegener's granulomatosis

Question 7

Primary mediators of anaphylaxis are all EXCEPT:

Accepted Answer

TNF

Answer

Histamine

Answer

Serotonin

Answer

Prostaglandins

Question 8

The immediate type of hypersensitivity in which histamine does not play a major role is:

Accepted Answer

Arthus reaction

Answer

Urticaria

Answer

Asthma

Answer

Anaphylaxis

Question 9

Epithelial granuloma is caused by which of the following?

Accepted Answer

Helper T-cells

Answer

Neutrophil

Answer

Cytotoxic T-cells

Answer

NK cells

Question 10

Which of the following cytokines is secreted by classically activated macrophages (M1)?

Accepted Answer

IL-1

Answer

IL-2

Answer

IL-4

Answer

IL-3

Immunopathology — MCQs

Immunopathology — MCQs

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