Blood and Immunity Practice Questions

Q: Eosinophils secrete all of the following except?

Eosinophilic chemotactic factor. ### Explanation The correct answer is **D. Eosinophilic chemotactic factor (ECF-A)**. The core concept to understand here is the difference between what a cell **secretes to kill pathogens** versus what **attracts the cell** to the site of inflammation. **1. Why Eosinophilic Chemotactic Factor is the correct answer:** Eosinophilic Chemotactic Factor (ECF-A) is **not** secreted by eosinophils; rather, it is primarily released by **mast cells and basophils** during degranulation. Its function is to act as a chemical "beacon" that recruits eosinophils to the site of an allergic reaction or parasitic infection. Eosinophils move toward this factor; they do not produce it. **2. Why the other options are incorrect:** Eosinophils are specialized granulocytes designed to kill large parasites (helminths). To do this, they secrete several potent substances: * **Major Basic Protein (MBP):** The most characteristic secretion of eosinophils. It is highly toxic to helminths and also triggers histamine release from mast cells. * **Hydrolytic Enzymes:** Eosinophils contain lysosomes filled with enzymes like acid phosphatase and nucleases to digest foreign material. * **Reactive Forms of Oxygen (ROS):** Like neutrophils, eosinophils undergo a "respiratory burst" to produce superoxide and hydrogen peroxide to kill pathogens. **High-Yield Clinical Pearls for NEET-PG:** * **Eosinophilia:** Defined as an absolute eosinophil count **>500/µL**. Common causes include **NAACP**: **N**eoplasia, **A**llergy/Asthma, **A**ddison’s disease, **C**onnective tissue disorders, and **P**arasites. * **Charcot-Leyden Crystals:** These are microscopic crystals found in the sputum of asthmatics, formed from the breakdown of eosinophil membrane proteins (Galectin-10). * **Eosinophil Peroxidase:** Distinct from myeloperoxidase (MPO) in neutrophils; it helps in the formation of hypohalous acids to destroy parasites.

Q: Which coagulation factor is not present in its active circulating form in the blood?

Factor III. **Explanation:** The correct answer is **Factor III (Tissue Factor)**. **Why Factor III is the correct answer:** Coagulation factors are generally synthesized by the liver and circulate in the plasma as inactive zymogens. However, **Factor III (Tissue Factor/Thromboplastin)** is a high-molecular-weight glycoprotein that is **not** present in the circulating blood under physiological conditions. It is an integral membrane protein found in the subendothelial layers (adventitia of blood vessels) and extravascular tissues. It only comes into contact with blood following vascular injury, where it binds with Factor VIIa to initiate the **Extrinsic Pathway** of the coagulation cascade. **Analysis of Incorrect Options:** * **Factor XI (Plasma Thromboplastin Antecedent):** This is a zymogen that circulates in the blood in its inactive form and is part of the Intrinsic Pathway. * **Factor X (Stuart-Prower Factor):** This is a Vitamin K-dependent serine protease that circulates in the plasma. It is the first factor of the Common Pathway. * **Factor XIII (Fibrin Stabilizing Factor):** This circulates in the plasma (bound to fibrinogen) and is activated by thrombin to cross-link fibrin clots. **High-Yield Clinical Pearls for NEET-PG:** * **Factor IV** is Calcium (the only inorganic factor). * **Factor VI** does not exist (formerly thought to be activated Factor V). * **Labile Factor:** Factor V (activity declines in stored blood). * **Stable Factor:** Factor VII (shortest half-life among all factors). * **Contact Factors:** Factors XI, XII, Prekallikrein, and High Molecular Weight Kininogen (HMWK). * **Vitamin K Dependent Factors:** II, VII, IX, and X.

Q: A father has blood group B and the mother has blood group AB. Which of the following blood groups are the children NOT likely to have?

O. ### Explanation The inheritance of ABO blood groups is based on **Mendelian genetics** and the principle of **multiple alleles**. The ABO gene has three alleles: $I^A$, $I^B$, and $i$ (where $i$ is recessive). **1. Why Option A (O) is Correct:** To have blood group **O**, a child must have the genotype **$ii$**, receiving one '$i$' allele from each parent. * **Mother:** Blood group AB has the genotype **$I^A I^B$**. She does not possess the '$i$' allele. * **Father:** Blood group B can have the genotype **$I^B I^B$** (homozygous) or **$I^B i$** (heterozygous). Since the mother cannot contribute an '$i$' allele, it is genetically impossible for the offspring to have blood group O ($ii$). **2. Why Other Options are Incorrect:** * **Option B (A):** If the father is heterozygous ($I^B i$) and the mother provides the $I^A$ allele, the child can be $I^A i$ (Group A). * **Option C (B):** If the father provides $I^B$ and the mother provides $I^B$, the child will be $I^B I^B$ or $I^B i$ (Group B). * **Option D (AB):** If the father provides $I^B$ and the mother provides $I^A$, the child will be $I^A I^B$ (Group AB). **Clinical Pearls for NEET-PG:** * **Codominance:** Alleles A and B are codominant (both expressed in AB group). * **Bombay Phenotype:** A rare condition where a person lacks the H-antigen. They may phenotypically test as Group O even if they genetically possess A or B alleles. * **Universal Donor/Recipient:** O negative is the universal donor (no antigens); AB positive is the universal recipient (no antibodies). * **Bernstein’s Formula:** Used to calculate allele frequencies in a population ($p+q+r = 1$).

Q: Which factor is required for erythrocyte stability?

All of the above. **Explanation:** Erythrocyte stability and survival depend on both **structural integrity** (the cytoskeleton) and **metabolic protection** (oxidative stress management). 1. **Structural Stability (Ankyrin & Spectrin):** The RBC membrane must be highly deformable to squeeze through narrow capillaries. This flexibility is provided by a protein network on the inner surface of the membrane. **Spectrin** is the primary cytoskeletal protein that forms a hexagonal meshwork. **Ankyrin** acts as the crucial "anchor," linking the spectrin network to the integral membrane protein (Band 3). Deficiencies in these proteins lead to membrane instability, resulting in conditions like **Hereditary Spherocytosis**. 2. **Metabolic Stability (NADPH):** Mature RBCs lack mitochondria and rely on the Hexose Monophosphate (HMP) Shunt to produce **NADPH**. NADPH is essential for maintaining a pool of reduced glutathione, which neutralizes reactive oxygen species (ROS). Without NADPH, hemoglobin denatures (forming Heinz bodies) and the cell membrane undergoes oxidative damage, leading to hemolysis. **Why "All of the above" is correct:** Stability is not just physical; it is biochemical. While Ankyrin and Spectrin provide the mechanical framework to prevent fragmentation, NADPH provides the chemical protection necessary to prevent premature destruction. **High-Yield Clinical Pearls for NEET-PG:** * **Hereditary Spherocytosis:** Most commonly due to a deficiency in **Ankyrin** (most frequent) or Spectrin. * **G6PD Deficiency:** The most common enzyme deficiency worldwide; it impairs **NADPH** production, leading to episodic hemolysis under oxidative stress. * **Vertical vs. Horizontal Interactions:** Defects in vertical interactions (Ankyrin/Band 3) cause Spherocytosis; defects in horizontal interactions (Spectrin dimers) cause **Hereditary Elliptocytosis**.

Q: All of the following are macrophages except—

Lymphocyte. **Explanation:** The question tests the concept of the **Mononuclear Phagocyte System (MPS)**, formerly known as the Reticuloendothelial System. This system consists of monocytes and their tissue-specific derivatives, which are specialized for phagocytosis and antigen presentation. **Why Lymphocyte is the correct answer:** Lymphocytes (B-cells, T-cells, and NK cells) are part of the **adaptive immune system** (and innate in the case of NK cells), but they are **not phagocytic cells**. They function through antibody production or cell-mediated cytotoxicity rather than engulfing and digesting pathogens. Therefore, they do not belong to the macrophage lineage. **Analysis of Incorrect Options:** * **Monocyte:** These are the precursor cells found in the blood. Once they migrate into tissues, they differentiate into mature macrophages. * **Kupffer Cells:** These are specialized, resident macrophages located in the **liver** (sinusoids). They are essential for clearing bacteria and debris from the portal circulation. * **Microglia:** These are the resident macrophages of the **Central Nervous System (CNS)**. They act as the primary active immune defense in the brain and spinal cord. **High-Yield Clinical Pearls for NEET-PG:** * **Tissue-Specific Macrophages to Remember:** * **Lung:** Alveolar macrophages (Dust cells). * **Skin:** Langerhans cells. * **Bone:** Osteoclasts. * **Kidney:** Mesangial cells. * **Placenta:** Hofbauer cells. * **Key Marker:** CD14 is a common surface marker used to identify monocytes and macrophages. * **Function:** Macrophages are the primary source of **Interleukin-1 (IL-1)**, which induces fever.

Q: At what stage do neutrophils first appear in peripheral blood?

Band forms. **Explanation:** The correct answer is **Band forms**. This question tests the understanding of granulopoiesis and the transition of cells from the bone marrow to the systemic circulation. **Why Band forms are correct:** Granulopoiesis follows a specific maturation sequence: Myeloblast → Promyelocyte → Myelocyte → Metamyelocyte → Band form → Mature Neutrophil (Segmented). Under normal physiological conditions, the bone marrow acts as a barrier, releasing only mature neutrophils and a small percentage (3-5%) of **Band forms** (immature neutrophils with non-segmented, curved nuclei) into the peripheral blood. Band forms represent the final stage of maturation before full segmentation and are the earliest stage routinely seen in a normal peripheral smear. **Why other options are incorrect:** * **Myeloblast:** This is the first identifiable myeloid precursor. It is confined to the bone marrow. Its presence in peripheral blood is always pathological (e.g., Acute Myeloid Leukemia). * **Promyelocyte:** Characterized by primary (azurophilic) granules, these cells stay within the marrow. * **Myelocyte:** This is the last stage capable of mitosis and the stage where secondary (specific) granules first appear. Like the stages above, it is restricted to the bone marrow in healthy individuals. **High-Yield Clinical Pearls for NEET-PG:** * **Left Shift:** An increase in band forms (>10%) in the peripheral blood is termed a "shift to the left," typically indicating an acute bacterial infection or inflammation. * **Myelocyte Stage:** High-yield fact—this is the stage where **specific granules** (e.g., alkaline phosphatase, lactoferrin) first appear. * **Leukemoid Reaction:** The presence of early precursors like myelocytes or metamyelocytes in the blood, often seen in severe infections, mimicking leukemia but with a high LAP (Leukocyte Alkaline Phosphatase) score.

Q: Which of the following coagulation factors is synthesized in the liver?

Factor VIII. ### Explanation The liver is the primary site for the synthesis of almost all coagulation factors. However, **Factor VIII (Anti-hemophilic factor)** is the notable exception. While it was historically thought to be produced in the liver, modern research confirms that Factor VIII is primarily synthesized in the **vascular endothelial cells** throughout the body, particularly within the liver (sinusoidal endothelium) and extrahepatic tissues (like the kidneys). #### Analysis of Options: * **Factor VIII (Correct):** Unlike other factors, Factor VIII is produced by endothelial cells. In patients with end-stage liver disease, Factor VIII levels often remain normal or are paradoxically elevated, making it a useful marker to differentiate liver failure from Disseminated Intravascular Coagulation (DIC). * **Factor II (Prothrombin):** Synthesized in the liver; it is a Vitamin K-dependent factor [1]. * **Factor VII (Stable Factor):** Synthesized in the liver; it has the shortest half-life (approx. 4–6 hours) among all factors, making the Prothrombin Time (PT) the first lab value to derange in acute liver injury [1]. * **Factor IX (Christmas Factor):** Synthesized in the liver; it is a Vitamin K-dependent factor involved in the intrinsic pathway [1]. #### High-Yield NEET-PG Pearls: 1. **Vitamin K-Dependent Factors:** II, VII, IX, X, Protein C, and Protein S [1]. 2. **Factor VIII & vWF:** Both are produced by endothelial cells (vWF is stored in Weibel-Palade bodies). 3. **Shortest Half-life:** Factor VII. 4. **Longest Half-life:** Factor II. 5. **Only Factor not synthesized in the liver:** Factor IV (Calcium). *Note: While Factor VIII is synthesized in liver endothelium, it is not synthesized by hepatocytes.*

Q: Decreased erythropoietin levels are seen in which of the following conditions?

End stage renal disease. ### Explanation **Correct Option: A. End stage renal disease (ESRD)** Erythropoietin (EPO) is a glycoprotein hormone primarily produced by the **interstitial fibroblasts in the peritubular capillary bed** of the renal cortex (approx. 85-90%). In ESRD, the progressive destruction of functional renal parenchyma and subsequent fibrosis lead to a profound loss of these EPO-producing cells. This deficiency is the primary cause of normocytic, normochromic anemia in chronic kidney disease. **Analysis of Incorrect Options:** * **B. Heart Failure:** Chronic heart failure often leads to a state of relative tissue hypoxia and decreased renal perfusion. This stimulates the Hypoxia-Inducible Factor (HIF) pathway, typically resulting in **increased** or compensatory EPO levels. * **C. Polycystic Kidney Disease (PKD):** Unlike other forms of renal failure, PKD is often associated with **normal or elevated** EPO levels. The cysts can cause local tissue hypoxia or the cyst-lining cells themselves may inappropriately secrete EPO, sometimes leading to polycythemia despite declining renal function. * **D. Advanced Liver Failure:** While the liver produces about 10-15% of adult EPO, liver failure does not typically cause a significant decrease in systemic EPO levels because the kidneys (the primary source) remain intact. Anemia in liver disease is usually multifactorial (e.g., hypersplenism, malnutrition). **High-Yield Facts for NEET-PG:** * **Stimulus for EPO:** The primary stimulus is **hypoxia** (detected by prolyl hydroxylase sensors), not the number of red blood cells. * **Site of Action:** EPO acts on the **CFU-E (Colony Forming Unit-Erythroid)** receptors in the bone marrow to prevent apoptosis of red cell precursors. * **Clinical Pearl:** Recombinant human erythropoietin (Epoetin alfa) is a mainstay treatment for anemia in ESRD, but it can cause **hypertension** as a common side effect.

Question 1

Eosinophils secrete all of the following except?

Accepted Answer

Eosinophilic chemotactic factor

Answer

Hydrolytic enzymes

Answer

Major basic protein

Answer

Reactive form of oxygen

Question 2

Which coagulation factor is not present in its active circulating form in the blood?

Accepted Answer

Factor III

Answer

Factor XI

Answer

Factor X

Answer

Factor XIII

Question 3

A father has blood group B and the mother has blood group AB. Which of the following blood groups are the children NOT likely to have?

Accepted Answer

O

Answer

A

Answer

B

Answer

AB

Question 4

Which factor is required for erythrocyte stability?

Accepted Answer

All of the above

Answer

Ankyrin

Answer

Spectrin

Answer

NADPH

Question 5

Citrate is a useful anticoagulant because of its ability to

Accepted Answer

Chelate calcium

Answer

Buffer basic groups of coagulation factors

Answer

Bind factor XII

Answer

Bind vitamin K

Question 6

Adding glucose to stored blood causes what?

Accepted Answer

Nutrition to red blood cells

Answer

Prevention of hemolysis

Answer

Increased acidosis of stored blood

Answer

Prevention of hyperkalemia

Question 7

All of the following are macrophages except—

Accepted Answer

Lymphocyte

Answer

Monocyte

Answer

Kupffer cell

Answer

Microglia

Question 8

At what stage do neutrophils first appear in peripheral blood?

Accepted Answer

Band forms

Answer

Myeloblast

Answer

Promyelocyte

Answer

Myelocyte

Question 9

Which of the following coagulation factors is synthesized in the liver?

Accepted Answer

Factor VIII

Answer

Factor II

Answer

Factor VII

Answer

Factor IX

Question 10

Decreased erythropoietin levels are seen in which of the following conditions?

Accepted Answer

End stage renal disease

Answer

Heart failure

Answer

Polycytic kidney disease

Answer

Advanced liver failure

Blood and Immunity — MCQs

Blood and Immunity — MCQs

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