Anatomy
1 questionsB cells are located in which region of lymph nodes?
NEET-PG 2015 - Anatomy NEET-PG Practice Questions and MCQs
Question 341: B cells are located in which region of lymph nodes?
- A. Paracortical region
- B. Cortical follicles (Correct Answer)
- C. Subcapsular region
- D. Medullary sinuses
Explanation: ***Cortical follicles*** - **B cells** are predominantly found within the **cortical follicles** of lymph nodes, where they mature and become activated upon encountering antigens [2]. - These follicles can be primary (inactive) or secondary (active, containing **germinal centers** for B cell proliferation and differentiation). *Paracortical region* - The **paracortical region** is primarily occupied by **T cells** and is the site where T cells interact with antigen-presenting cells [1]. - While it's adjacent to B cell areas, it's not the primary location for B cells. *Medullary sinuses* - **Medullary sinuses** are channels in the medulla of the lymph node, containing macrophages and plasma cells, which are *differentiated B cells*. - They are not the primary residence for undifferentiated B cells. *Subcapsular region* - **Subcapsular region** is the space immediately beneath the capsule of the lymph node where lymph initially enters. - It contains macrophages and dendritic cells that sample antigens but is not a primary B cell zone.
Dermatology
1 questionsHLA-Cw6 is associated with
NEET-PG 2015 - Dermatology NEET-PG Practice Questions and MCQs
Question 341: HLA-Cw6 is associated with
- A. Behcet's disease
- B. Pemphigus vulgaris
- C. Psoriasis vulgaris (Correct Answer)
- D. Myasthenia gravis
Explanation: ***Psoriasis vulgaris*** - **HLA-Cw6** is the **strongest genetic risk factor** associated with an increased susceptibility to psoriasis vulgaris, particularly early-onset forms. - Its presence is linked to a more severe and widespread presentation of the disease. *Myasthenia gravis* - This autoimmune disorder is primarily associated with **HLA-DR3** and **HLA-B8**, and autoantibodies against the acetylcholine receptor. - While other HLA alleles may be involved, **HLA-Cw6** is not a primary or strong genetic association for myasthenia gravis. *Behcet's disease* - **HLA-B51** is the most significant genetic association with Behcet's disease, particularly in populations of Middle Eastern and East Asian descent. - Symptoms include **recurrent oral and genital ulcers**, **uveitis**, and skin lesions. *Pemphigus vulgaris* - This autoimmune blistering disease is strongly associated with **HLA-DR4** and **HLA-DRw6**, especially in individuals of Jewish descent. - It involves autoantibodies targeting **desmoglein 1 and 3**, leading to acantholysis within the epidermis.
Internal Medicine
3 questionsExtremities are warm in which type of shock
In which condition is Serum Amyloid Associated (SAA) protein most commonly found?
Shrinking Lung Syndrome is seen in:
NEET-PG 2015 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 341: Extremities are warm in which type of shock
- A. Hypovolemic shock
- B. Neurogenic shock (Correct Answer)
- C. Anaphylactic shock
- D. Cardiogenic shock
Explanation: ***Neurogenic shock*** - This type of shock is caused by a loss of **sympathetic tone**, leading to widespread **vasodilation** and a relative hypovolemia, resulting in warm, flushed extremities. - The decreased systemic vascular resistance causes **blood pooling** in the periphery rather than being shunted to vital organs, contributing to the warm skin. *Hypovolemic shock* - Characterized by **decreased blood volume**, leading to activation of the sympathetic nervous system and **vasoconstriction** to shunt blood to vital organs. - This results in **cold, clammy extremities** due to reduced peripheral perfusion. *Anaphylactic shock* - An acute, life-threatening hypersensitivity reaction involving massive release of inflammatory mediators, causing widespread **vasodilation** and increased vascular permeability. - While it can cause flushing and warmth initially due to vasodilation, it often leads to significant fluid shifts and can present with both warm and then cool, clammy skin as shock progresses. *Cardiogenic shock* - Caused by **severe cardiac pump failure**, leading to decreased cardiac output and poor tissue perfusion. - The body's compensatory mechanisms, including sympathetic activation, cause **peripheral vasoconstriction**, leading to **cold, clammy extremities**.
Question 342: In which condition is Serum Amyloid Associated (SAA) protein most commonly found?
- A. Alzheimer's disease
- B. Malignant hypertension
- C. Chronic inflammatory states (Correct Answer)
- D. Chronic renal failure
- E. Acute myocardial infarction
Explanation: ***Chronic inflammatory states*** [1][2] - Serum amyloid-associated protein is elevated in response to **chronic inflammation**, such as in rheumatic diseases and infections [1][2]. - It serves as a **biomarker** indicating systemic inflammation and is part of the **acute-phase response** [1]. *Chronic renal failure* - While renal failure can lead to amyloidosis, it is not a direct cause of serum amyloid-associated protein elevation. - **Renal impairment** is more associated with a decrease in clearance rather than production of amyloid proteins. *Alzheimer's disease* - Although amyloid plaques are a hallmark of Alzheimer's, they are related to **A-beta peptide**, not serum amyloid-associated protein. - Alzheimer's pathology primarily involves **neurodegeneration** rather than inflammatory response. *Malignant hypertension* - Malignant hypertension primarily affects the **vascular system** and does not directly involve the production of serum amyloid-associated protein. - It is characterized by end-organ damage, rather than a state of chronic inflammation. *Chronic inflammatory conditions like RA, TB & leprosy, osteomyelitis, ankylosing spondylitis, IBD, bronchiectasis, some tumors* [1][2] - While these conditions can be associated with systemic inflammation, they are too specific and do not comprehensively encompass the broader concept of **chronic inflammatory states**. - This option fails to highlight that serum amyloid-associated protein is a marker for **various chronic inflammatory states** beyond just those listed [1].
Question 343: Shrinking Lung Syndrome is seen in:
- A. SLE (Correct Answer)
- B. Rheumatoid Arthritis
- C. Scleroderma
- D. Sarcoidosis
Explanation: ***SLE*** - **Shrinking lung syndrome (SLS)** is a rare but recognized pulmonary manifestation of **systemic lupus erythematosus (SLE)** [1]. - It is characterized by **dyspnea**, **pleuritic chest pain**, and elevated diaphragms with reduced lung volumes, often without significant interstitial lung disease [1]. *Rheumatoid Arthritis* - While **rheumatoid arthritis** can cause various lung manifestations like **interstitial lung disease (ILD)**, pleural effusions, and rheumatoid nodules, **shrinking lung syndrome** is not typically associated with it [2]. - Lung disease in RA often involves **pulmonary fibrosis** or bronchiolitis, differing from the restrictive physiology of SLS. *Scleroderma* - **Scleroderma (Systemic Sclerosis)** commonly affects the lungs, primarily leading to **interstitial lung disease (ILD)** and **pulmonary hypertension** [1]. - **Shrinking lung syndrome**, with its characteristic restrictive pattern and elevated diaphragms, is not a typical presentation of lung involvement in scleroderma. *Sarcoidosis* - **Sarcoidosis** is characterized by the formation of **non-caseating granulomas**, primarily affecting the lungs and lymph nodes. - Lung involvement in sarcoidosis typically presents as **interstitial lung disease** or nodular infiltrates, not the distinct features of **shrinking lung syndrome** [3].
Microbiology
4 questionsInterleukin 2 is produced by
IFN-gamma is produced by
The process by which antigen-specific B lymphocytes are selected and activated to proliferate and produce antibodies is called:
In the context of immune response, which of the following cell types does not express MHC class II molecules?
NEET-PG 2015 - Microbiology NEET-PG Practice Questions and MCQs
Question 341: Interleukin 2 is produced by
- A. T helper cells 1 (Correct Answer)
- B. T helper cells 2
- C. Natural killer cells
- D. Basophils
Explanation: ***T helper cells 1*** - **T helper 1 (Th1) cells** are a primary source of **interleukin-2 (IL-2)**, which is crucial for the proliferation and survival of T cells. - IL-2 acts as a **T-cell growth factor**, promoting the expansion of activated T cells, including cytotoxic T lymphocytes. *T helper cells 2* - **T helper 2 (Th2) cells** primarily produce cytokines like **IL-4, IL-5, IL-6, IL-10, and IL-13**, which are involved in humoral immunity and allergic responses. - While Th2 cells are important for immune responses, they are not major producers of IL-2. *Natural killer cells* - **Natural killer (NK) cells** are part of the innate immune system and produce cytokines such as **interferon-gamma (IFN-$\gamma$)** and **tumor necrosis factor-alpha (TNF-$\alpha$)**. - They are not a significant source of IL-2, which is primarily a T-cell derived growth factor. *Basophils* - **Basophils** are granulocytes involved in allergic reactions and anti-parasitic immunity, producing mediators like **histamine** and cytokines such as **IL-4** and **IL-13**. - Basophils do not produce IL-2; their role is distinct in the immune response compared to T cells.
Question 342: IFN-gamma is produced by
- A. Macrophages
- B. T-cells (Correct Answer)
- C. Neutrophils
- D. B-cells
Explanation: ***T-cells*** - **Interferon-gamma (IFN-γ)** is a crucial cytokine primarily produced by **activated T-lymphocytes**, especially **Th1 cells** and **cytotoxic T lymphocytes (CTLs)**. - Natural killer (NK) cells also produce **IFN-γ**, which plays a key role in **antiviral** and **antitumor immunity**, as well as in promoting **Type 1 immune responses**. *Macrophages* - While macrophages are **responsive to IFN-γ** (e.g., becoming activated), they are not the primary producers of this cytokine. - Macrophages primarily produce other cytokines such as **IL-1, IL-6, TNF-alpha**, and **IL-12** in response to infection or inflammation. *Neutrophils* - **Neutrophils** are key phagocytes in the innate immune system and are primarily involved in engulfing and killing pathogens. - They are not known to be a significant source of **IFN-γ** production; their main defensive mechanisms involve **phagocytosis**, **degranulation**, and **NETosis**. *B-cells* - **B-cells** are central to humoral immunity, specializing in **antibody production** and acting as **antigen-presenting cells**. - They generally do not produce **IFN-γ**; instead, their cytokine repertoire includes **IL-10**, **IL-6**, and **lymphotoxin**.
Question 343: The process by which antigen-specific B lymphocytes are selected and activated to proliferate and produce antibodies is called:
- A. Clonal selection (Correct Answer)
- B. Class switching
- C. Group switching
- D. Hybridisation
Explanation: ***Clonal selection*** - **Clonal selection** is the fundamental process by which an antigen-specific B lymphocyte is **selected** when its B cell receptor (BCR) recognizes and binds to a matching antigen. - This binding triggers the B cell to become **activated**, **proliferate** (undergo clonal expansion), and **differentiate** into plasma cells that produce antibodies specific to that antigen. - This process is the cornerstone of **adaptive immunity**, ensuring that only B cells with receptors matching the encountered antigen are stimulated to respond. *Class switching* - **Class switching** (isotype switching) occurs AFTER clonal selection and activation. - It allows already-activated B cells to change the **antibody class** they produce (from IgM to IgG, IgA, or IgE) while maintaining the **same antigen specificity**. - This process modifies effector functions but does NOT involve the initial selection and activation of antigen-specific B cells. *Group switching* - This is not a recognized term in immunology. - It does not describe any standard process of B cell activation or antibody production. *Hybridisation* - **Hybridization** refers to the formation of double-stranded nucleic acids from complementary strands or the creation of hybrid cells (e.g., hybridomas for monoclonal antibody production). - It is not the physiological process by which B lymphocytes are selected and activated in response to antigen exposure.
Question 344: In the context of immune response, which of the following cell types does not express MHC class II molecules?
- A. Cortical macrophages
- B. Neutrophils
- C. Medullary macrophages
- D. NK cells (Correct Answer)
Explanation: ***NK cells*** - **Natural Killer (NK) cells)** are innate lymphocytes that do **NOT express MHC class II molecules** under any circumstances. - NK cells use alternative recognition mechanisms (KIRs, activating receptors) to detect target cells, primarily recognizing the **absence of MHC class I** or stress-induced ligands. - They function in innate immunity without antigen presentation capability. - **This is the best answer** as NK cells never express MHC class II, making them distinctly different from professional APCs. *Cortical macrophages* - **Cortical macrophages** in lymphoid organs are professional **antigen-presenting cells (APCs)** that constitutively express **MHC class II molecules**. - They present processed antigens to CD4+ T helper cells, playing a crucial role in initiating adaptive immune responses. *Medullary macrophages* - **Medullary macrophages** are also professional APCs that constitutively express **MHC class II molecules**. - They participate in antigen presentation and immune surveillance within the medullary regions of lymphoid tissues. *Neutrophils* - Neutrophils are granulocytes that **typically do not constitutively express MHC class II molecules** in their resting state. - However, under certain inflammatory conditions with prolonged stimulation (IFN-γ, GM-CSF), neutrophils can be induced to express low levels of MHC class II. - While neutrophils generally lack MHC class II, **NK cells are the more definitive answer** as they never express MHC class II under any physiological or pathological conditions.
Physiology
1 questionsInterleukin responsible for Pyrexia is:
NEET-PG 2015 - Physiology NEET-PG Practice Questions and MCQs
Question 341: Interleukin responsible for Pyrexia is:
- A. IL1 (Correct Answer)
- B. IL4
- C. IL3
- D. IL8
Explanation: ***IL1*** - **Interleukin-1 (IL-1)** is a primary **endogenous pyrogen**, directly acting on the thermoregulatory center in the hypothalamus to induce fever. - It stimulates the production of **prostaglandin E2 (PGE2)**, which then alters the hypothalamic set point, leading to increased body temperature. *IL3* - **Interleukin-3 (IL-3)** is a **hematopoietic growth factor** that primarily stimulates the proliferation and differentiation of hematopoietic stem cells. - Its main role is in the development of various blood cell lineages, not directly in inducing fever. *IL4* - **Interleukin-4 (IL-4)** is a key cytokine in **allergic reactions** and **Th2 immune responses**, promoting B cell activation and IgE production. - It does not directly cause pyrexia; its primary functions are related to humoral immunity and immune regulation. *IL8* - **Interleukin-8 (IL-8)**, also known as **CXCL8**, is a potent **chemotactic factor** for neutrophils and other immune cells. - Its main function is to recruit inflammatory cells to sites of infection or injury, not to induce fever directly.