Blood and Immunity Practice Questions

Q: An individual with AB blood group has which of the following agglutinins?

Neither anti-A nor anti-B. ### Explanation **Concept:** The ABO blood grouping system is based on **Landsteiner’s Law**, which states that if an antigen (agglutinogen) is present on the Red Blood Cell (RBC) membrane, the corresponding antibody (agglutinin) must be absent from the plasma. Conversely, if an antigen is absent on the RBC, the corresponding antibody must be present in the plasma. In an individual with **AB blood group**, both **Antigen A and Antigen B** are present on the surface of the RBCs. To prevent auto-agglutination (destruction of one's own cells), the body does not produce antibodies against these antigens. Therefore, the plasma contains **neither anti-A nor anti-B antibodies**. **Analysis of Options:** * **Option B (Correct):** As explained, the presence of both A and B antigens necessitates the absence of both antibodies in the plasma. * **Option A:** This is characteristic of **Blood Group O**, where neither antigen is present on the RBC, leading to the production of both anti-A and anti-B antibodies. * **Option C:** Anti-A antibodies are found in individuals with **Blood Group B**. * **Option D:** Anti-B antibodies are found in individuals with **Blood Group A**. **High-Yield Facts for NEET-PG:** * **Universal Recipient:** AB positive is the universal recipient because it lacks anti-A and anti-B antibodies, meaning it won't react against transfused RBCs. * **Universal Donor:** O negative is the universal donor because it lacks A, B, and Rh antigens. * **Agglutinins:** These are typically **IgM** antibodies that do not cross the placenta (unlike Rh antibodies, which are IgG). * **Bombay Blood Group:** Lacks the H-antigen; these individuals have anti-A, anti-B, and anti-H antibodies.

Q: What is the lifespan of platelets and neutrophils, respectively?

8-9 days and 5 days. ### Explanation The correct answer is **Option A: 8-9 days and 5 days.** **1. Understanding the Lifespan (Kinetics):** * **Platelets (Thrombocytes):** These are anuclear fragments derived from megakaryocytes in the bone marrow. Their average lifespan in the peripheral blood is approximately **8 to 11 days** (commonly cited as 8–9 days in standard textbooks like Guyton and Ganong). After this period, they are sequestered and destroyed primarily by the splenic macrophages. * **Neutrophils (PMNs):** These are the most abundant leukocytes but have a relatively short half-life. Once released from the bone marrow, they circulate in the blood for about **6 to 10 hours** before migrating into tissues, where they survive for **2 to 5 days**. In the context of NEET-PG, "5 days" is the standard representative figure for their total functional lifespan. **2. Analysis of Incorrect Options:** * **Option B & C:** Mention **120 days**, which is the classic lifespan of a mature **Red Blood Cell (RBC)**. RBCs have a longer lifespan because they lack a nucleus and mitochondria, focusing entirely on hemoglobin transport. * **Option D:** Reverses the order. While both numbers are used, platelets live longer than the tissue-resident lifespan of neutrophils. **3. NEET-PG High-Yield Clinical Pearls:** * **Storage:** 1/3rd of the body's platelets are stored in the **spleen** at any given time (Splenic Pool). In splenomegaly, platelet counts may drop due to increased sequestration. * **Transfusion:** Because of their short lifespan and the risk of bacterial growth, pooled platelets are stored at room temperature and have a shelf life of only **5 days**. * **Neutrophil Kinetics:** In acute infections, the "Left Shift" refers to the premature release of immature neutrophils (band cells) because the 5-day supply is rapidly exhausted.

Q: Rh antibodies are:

IgM. **Explanation:** The correct answer is **A. IgM**. **Medical Concept:** Rh antibodies are primarily produced following exposure to Rh-positive red blood cells in an Rh-negative individual (isoimmunization). The **initial immune response** (primary response) to the D-antigen results in the production of **IgM** antibodies. These are pentameric, large molecules that do not cross the placenta. However, upon subsequent exposure or as the immune response matures (secondary response), the body undergoes class switching to produce **IgG** antibodies. While clinical complications like Hemolytic Disease of the Newborn (HDN) are caused by IgG (which crosses the placenta), the fundamental physiological classification of the initial Rh antibody formed is IgM. **Analysis of Incorrect Options:** * **B. IgA:** Found primarily in secretions (colostrum, saliva, tears) and mucosal surfaces; it is not involved in Rh incompatibility. * **C. IgE:** Mediates Type I hypersensitivity reactions (allergies) and defense against helminthic parasites. * **D. IgD:** Primarily acts as an antigen receptor on the surface of B-lymphocytes; its role in serum is minimal and unrelated to blood group antigens. **High-Yield NEET-PG Pearls:** * **ABO Antibodies:** Naturally occurring, predominantly **IgM** (cannot cross placenta). * **Rh Antibodies:** Immune-mediated, initially **IgM**, then predominantly **IgG** (can cross placenta). * **Anti-D (RhoGAM):** Given to Rh-negative mothers to prevent sensitization; it is an IgG preparation that destroys fetal Rh+ cells before the mother's immune system can react. * **Direct Coombs Test:** Detects antibodies already bound to the surface of RBCs (used to diagnose HDN).

Q: Blood cells arise in bone marrow and are subject to what type of renewal process?

Regular renewal. **Explanation:** The correct answer is **Regular renewal**. Hematopoiesis is a continuous and highly regulated process. Blood cells (erythrocytes, leukocytes, and platelets) have finite lifespans—ranging from a few hours (neutrophils) to 120 days (RBCs). To maintain physiological homeostasis, the bone marrow must produce billions of new cells daily to replace those that are aged or destroyed. This constant turnover is termed **regular renewal**. It ensures that the peripheral blood count remains within a narrow therapeutic range despite the continuous loss of cells. **Analysis of Options:** * **Irregular renewal:** This is incorrect because hematopoiesis is not haphazard. It follows a strict circadian and feedback-driven rhythm (mediated by erythropoietin, G-CSF, etc.) to match production with demand. * **Infrequent renewal:** This is incorrect as blood cells are among the most rapidly dividing and replaced cell populations in the body. "Infrequent renewal" would apply to tissues like the myocardium or neurons, which have limited regenerative capacity. **High-Yield NEET-PG Pearls:** * **Site of Hematopoiesis:** In adults, it occurs in the **red bone marrow** (primarily membranous bones like the pelvis, sternum, and vertebrae). In the fetus, the **liver** is the chief site during the second trimester. * **Pluripotent Stem Cells:** All blood cells originate from **CD34+** hematopoietic stem cells. * **Kinetics:** The bone marrow produces approximately $10^{11}$ to $10^{12}$ new blood cells daily under steady-state conditions. * **Clinical Correlation:** A failure in this regular renewal process leads to **Aplastic Anemia** (pancytopenia).

Q: All of the following stem cell populations are found within the bone marrow, except?

Myoblast Progenitor cells. ### Explanation The bone marrow is a complex microenvironment (niche) that serves as the primary site for hematopoiesis and houses various multipotent stem cell populations. **Why Myoblast Progenitor Cells are the Correct Answer:** **Myoblast progenitor cells** (satellite cells) are the precursors to skeletal muscle fibers. They are found located between the sarcolemma and the basal lamina of **muscle fibers**, not in the bone marrow. Their primary role is the repair and regeneration of muscle tissue following injury. **Analysis of Incorrect Options:** * **Hematopoietic Stem Cells (HSCs):** These are the most well-known residents of the bone marrow. They are multipotent cells responsible for the constant production of all blood cell lineages (RBCs, WBCs, and platelets). * **Mesenchymal Stem Cells (MSCs):** Also known as marrow stromal cells, these are multipotent cells that can differentiate into non-hematopoietic lineages, including **osteoblasts** (bone), **chondrocytes** (cartilage), and **adipocytes** (fat). * **Endothelial Progenitor Cells (EPCs):** These cells reside in the bone marrow and can be mobilized into the circulation to participate in angiogenesis and the repair of blood vessel linings. **High-Yield Clinical Pearls for NEET-PG:** * **Niche Concept:** The bone marrow "niche" consists of cellular components (osteoblasts, endothelial cells) and humoral factors (CXCL12/SDF-1) that regulate stem cell quiescence and proliferation. * **CD Markers:** HSCs are typically identified by the presence of **CD34+** and **CD117+ (c-kit)**, and the absence of lineage-specific markers (Lin-). * **Transdifferentiation:** While MSCs primarily form bone/cartilage/fat, they are a major focus of regenerative medicine due to their potential to differentiate into various tissues under specific experimental conditions.

Q: Which of the following cell types are classified as large granular lymphocytes?

NK cells. **Explanation:** **Natural Killer (NK) cells** are the correct answer because they are morphologically defined as **Large Granular Lymphocytes (LGLs)**. Unlike small lymphocytes (B and T cells), NK cells possess a more abundant cytoplasm containing prominent azurophilic granules. These granules house cytotoxic proteins like **perforins and granzymes**, which are essential for the innate immune response against virally infected cells and tumor cells. **Analysis of Incorrect Options:** * **B cells and T cells (Options A & C):** These are typically classified as **small, non-granular lymphocytes**. They have a high nuclear-to-cytoplasmic ratio with very little cytoplasm and generally lack visible granules under light microscopy. While a small subset of T cells (specifically activated CD8+ T cells) can exhibit an LGL morphology, the classic and primary definition of an LGL refers to NK cells. * **Plasma cells (Option D):** These are terminally differentiated B cells. Morphologically, they are characterized by an eccentric "cartwheel" nucleus and a prominent perinuclear clear zone (Golgi apparatus), but they are not classified as large granular lymphocytes. **High-Yield Pearls for NEET-PG:** * **Surface Markers:** NK cells are identified by the presence of **CD56 and CD16**, and the absence of CD3 (T-cell marker). * **Function:** They provide the first line of defense and do not require prior sensitization (MHC-independent killing). * **Clinical Correlation:** **LGL Leukemia** is a rare lymphoproliferative disorder that can arise from either NK cells or T cells, often presenting with neutropenia and splenomegaly. * **Chediak-Higashi Syndrome:** A condition where NK cell function is impaired due to defective granule formation/trafficking.

Q: A patient with blood group O can safely receive plasma from which blood group donor?

Group A, B, and AB. ### Explanation The core concept in transfusion medicine is understanding the difference between **Whole Blood/Packed Red Blood Cell (PRBC)** transfusion and **Plasma** transfusion. **1. The Underlying Medical Concept:** * **PRBC Transfusion:** We worry about the **antigens** on the donor's RBCs and the **antibodies** in the recipient's plasma. * **Plasma Transfusion:** We worry about the **antibodies** present in the donor's plasma and how they will react with the **antigens** on the recipient's RBCs. A patient with **Blood Group O** has **no A or B antigens** on their red blood cells. Because there are no antigens for antibodies to attack, they can safely receive plasma containing Anti-A antibodies (from Group B), Anti-B antibodies (from Group A), or both. Therefore, plasma from A, B, or AB donors will not cause hemolysis in a Group O recipient. **2. Analysis of Options:** * **Options A & B:** While Group O can receive plasma from A or B, these options are "incomplete." Since Group O RBCs lack antigens, they are compatible with plasma from any group. * **Option C:** Group AB plasma is the "Universal Donor" for plasma because it contains **no antibodies**. While safe, it is not the *only* safe option for a Group O recipient. * **Option D (Correct):** Since Group O RBCs are "antigen-neutral," they are compatible with any plasma regardless of the antibody content. **3. NEET-PG High-Yield Pearls:** * **Universal Donor (RBCs):** Group O Negative (No antigens). * **Universal Recipient (RBCs):** Group AB Positive (No antibodies). * **Universal Donor (Plasma):** Group AB (No antibodies in plasma). * **Universal Recipient (Plasma):** Group O (No antigens on RBCs to be attacked). * **Landsteiner’s Law:** States that if an antigen is present on RBCs, the corresponding antibody must be absent in the plasma (and vice versa). This law does not apply to Group AB (no antibodies) or Group O (no antigens).

Q: What is the normal leukocyte count per cubic millimeter of blood?

4,000-11,000. **Explanation:** The Total Leukocyte Count (TLC) represents the number of white blood cells (WBCs) circulating in the peripheral blood. In a healthy adult, the physiological range is **4,000 to 11,000 cells per cubic millimeter (mm³)**. These cells are essential components of the immune system, categorized into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes). * **Why Option B is correct:** This range is the globally accepted clinical standard. Variations slightly below or above this range are termed leukopenia and leukocytosis, respectively. * **Why Options A, C, and D are incorrect:** These ranges do not align with standard physiological data. While a count of 8,000 (Option C) or 14,000 (Option D) might occur in specific individuals or during mild inflammation, they do not represent the established "normal" baseline range for the general population. **High-Yield Clinical Pearls for NEET-PG:** 1. **Leukocytosis:** A TLC >11,000/mm³. Common causes include acute bacterial infections (neutrophilia), viral infections (lymphocytosis), or physiological stress (exercise, pregnancy). 2. **Leukopenia:** A TLC 50,000/mm³) mimicking leukemia, usually due to severe infection or inflammation, but characterized by a high **LAP (Leukocyte Alkaline Phosphatase) score**, unlike Chronic Myeloid Leukemia (CML). 4. **Newborns:** It is important to remember that newborns have a much higher normal TLC, often ranging from 10,000 to 25,000/mm³.

Q: What is the longest lifespan among the following blood cells?

Macrophages. ### Explanation The lifespan of blood cells varies significantly based on their function and environment. Among the options provided, **Macrophages** possess the longest lifespan. **1. Why Macrophages are the Correct Answer:** Monocytes circulate in the blood for about 10–20 hours before migrating into tissues, where they differentiate into **Macrophages**. Once in the tissues (e.g., Kupffer cells in the liver, Alveolar macrophages in the lungs), they can survive for **several months to even years**. Their longevity is essential for their role in chronic inflammation, antigen presentation, and tissue remodeling. **2. Why the Other Options are Incorrect:** * **Red Blood Cells (RBCs):** These have a fixed average lifespan of **120 days** in adults. While longer than most white blood cells, they are eventually sequestered and destroyed by the splenic sinusoids. * **Platelets (Thrombocytes):** These are cell fragments with a short lifespan of approximately **7 to 10 days**. They are primarily involved in hemostasis and are rapidly consumed or cleared by the spleen. * **Neutrophils:** These are the "first responders" of the immune system but have a very short half-life. They circulate for about **6–12 hours** and survive in tissues for only **2–5 days** before undergoing apoptosis. **3. NEET-PG High-Yield Clinical Pearls:** * **Memory Cells:** If "Memory B or T cells" were an option, they would be the correct answer, as they can persist for **decades**. * **RBC Lifespan:** It is shorter in neonates (approx. 60–90 days) and decreased in conditions like Hereditary Spherocytosis or Sickle Cell Anemia. * **Platelet Storage:** Because of their short 7–10 day lifespan, donated platelets can only be stored for **5 days** at room temperature, unlike RBCs which can be stored for 35–42 days.

Question 1

What is the Fahraeus Lindquist effect?

Accepted Answer

Increase in viscosity in vessels less than 0.5-1 mm in diameter

Answer

Decrease in viscosity in vessels less than 0.5-1 mm in diameter

Answer

Increase in viscosity in vessels more than 0.5-1 mm in diameter

Answer

Decrease in viscosity in vessels more than 0.5-1 mm in diameter

Question 2

An individual with AB blood group has which of the following agglutinins?

Accepted Answer

Neither anti-A nor anti-B

Answer

Anti-A and anti-B

Answer

Anti-A

Answer

Anti-B

Question 3

What is the lifespan of platelets and neutrophils, respectively?

Accepted Answer

8-9 days and 5 days

Answer

120 days and 5 days

Answer

5 days and 120 days

Answer

5 days and 8-9 days

Question 4

Rh antibodies are:

Accepted Answer

IgM

Answer

IgA

Answer

IgE

Answer

IgD

Question 5

Blood cells arise in bone marrow and are subject to what type of renewal process?

Accepted Answer

Regular renewal

Answer

Irregular renewal

Answer

Infrequent renewal

Answer

None of the above

Question 6

All of the following stem cell populations are found within the bone marrow, except?

Accepted Answer

Myoblast Progenitor cells

Answer

Endothelial Progenitor cells

Answer

Mesenchymal stem cells

Answer

Hematopoietic stem cells

Question 7

Which of the following cell types are classified as large granular lymphocytes?

Accepted Answer

NK cells

Answer

B cells

Answer

T cells

Answer

Plasma cells

Question 8

A patient with blood group O can safely receive plasma from which blood group donor?

Accepted Answer

Group A, B, and AB

Answer

Group A only

Answer

Group B only

Answer

Group AB only

Question 9

What is the normal leukocyte count per cubic millimeter of blood?

Accepted Answer

4,000-11,000

Answer

8,000-15,000

Answer

5,000-8,000

Answer

7,000-14,000

Question 10

What is the longest lifespan among the following blood cells?

Accepted Answer

Macrophages

Answer

Red Blood Cells (RBC)

Answer

Platelets

Answer

Neutrophils

Blood and Immunity — MCQs

Blood and Immunity — MCQs

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