Immune Response Mechanisms Quiz
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Questions and Answers

Which type of proteins are responsible for the destruction of organisms/toxins along with enzymes and neutrophil extracellular traps?

  • AMPs (correct)
  • Cytokines
  • Chemokines
  • Antibodies

Which cell types initially produce inflammatory mediators at sites of infection or damage?

  • Basophils
  • Mast cells (correct)
  • Macrophages (MFs)
  • Neutrophils

Which of the following is NOT a function of 'alarm' cytokines during the acute phase of inflammation?

  • Fever
  • Increased vascular permeability
  • Decreased adhesion molecule expression (correct)
  • Production of Acute Phase Proteins

What is the role of chemokines in the inflammatory response?

<p>Attracting leukocytes towards a chemical signal (A)</p> Signup and view all the answers

Which proteins are involved in indirect recognition within the complement activation pathways?

<p>Antibodies (B)</p> Signup and view all the answers

What is the main characteristic of cytokines among the various mediators in inflammation?

<p>They facilitate communication between white blood cells (A)</p> Signup and view all the answers

Which cytokines are considered 'anti-inflammatory'?

<p>IL-10 and TGF-β (D)</p> Signup and view all the answers

What is the role of IL-12 and IL-18?

<p>Induce differentiation of pro-inflammatory T cells (D)</p> Signup and view all the answers

Which cytokine is known for recruiting macrophages to sites of damage/infection?

<p>IFNγ (C)</p> Signup and view all the answers

What is the main function of type I interferons (IFNa and b)?

<p>Have antiviral properties within infected cells (C)</p> Signup and view all the answers

What defines chemokines and their function?

<p>Their ability to stimulate migration &amp; activation of cells towards a source (D)</p> Signup and view all the answers

What is the role of catalase, superoxide dismutase, and glutathione in the context of free radicals?

<p>Acting as free radical scavengers (B)</p> Signup and view all the answers

Which enzyme is responsible for converting oxygen into superoxide, peroxide, or hydroxyl anion with unpaired electrons?

<p>Nicotinamide Adenine Diphosphate (NADPH) oxidase (C)</p> Signup and view all the answers

What is the primary physiological effect of inducible Nitric oxide synthase (iNOS)?

<p>Antimicrobial activity (B)</p> Signup and view all the answers

Where are most microbicidal mediators produced within the immune system?

<p>Lysosomes of macrophages (C)</p> Signup and view all the answers

How do some pathogens escape the mechanisms of professional phagocytes?

<p>By triggering autophagy (A)</p> Signup and view all the answers

What is the consequence of combining Nitric Oxide (NO) with superoxide?

<p>Formation of peroxynitrite, a potent molecule (A)</p> Signup and view all the answers

Which enzyme is mainly found in Neutrophil granules and is most active at alkaline pH?

<p>Elastase (D)</p> Signup and view all the answers

What is the main function of Defensins in the immune system?

<p>Form pores in cytoplasmic membranes (B)</p> Signup and view all the answers

Which enzyme is an acid hydrolase known for breaking down phosphates and sulphates?

<p>Sulphatases (B)</p> Signup and view all the answers

What is the primary effect of Tumour necrosis factor alpha (TNFa) in the immune system?

<p>Cytotoxic to tumour cells (B)</p> Signup and view all the answers

What characteristic makes Cationic proteins like elastase, cathepsin G, and proteinase 3 specific for microbial cells?

<p>+ve charged polypeptides (C)</p> Signup and view all the answers

How do Acid hydrolases like glycosidases contribute to immune responses?

<p>Break down glycosides (A)</p> Signup and view all the answers

Which enzymes are responsible for the production of Prostaglandins?

<p>Cyclooxygenases (COX-1, COX-2) (B)</p> Signup and view all the answers

What is the major target of 'anti-inflammatory' pain killers?

<p>Cyclooxygenases (COX-1, COX-2) (A)</p> Signup and view all the answers

Which eicosanoid is described as having 'hormone-like' effects?

<p>Prostaglandins (B)</p> Signup and view all the answers

What is the role of PGE2 in the body?

<p>Induce fever by acting on hypothalamus (D)</p> Signup and view all the answers

Which cells secrete products that play a role in cellular movement during inflammation?

<p>Macrophages (B)</p> Signup and view all the answers

What term describes the movement of white blood cells or fluid from the lumen of blood vessels into tissues?

<p>Extravasation (D)</p> Signup and view all the answers

During the 'Ingestion' stage of phagocytosis, pseudopodia form and surround the particle to engulf it in a membrane-bound vesicle called a PHAGOSOME.

<p>True (A)</p> Signup and view all the answers

The four main features of an innate immune response include Anatomical, Physiological, Lymphocytic, and Inflammatory barriers/features.

<p>False (B)</p> Signup and view all the answers

Pattern Recognition Receptors (PRRs) play a significant role in phagocytosis and innate immune cell activation.

<p>True (A)</p> Signup and view all the answers

Complement system activation involves only one mechanism that leads to pathogen destruction.

<p>False (B)</p> Signup and view all the answers

Cells involved in cell-mediated innate immunity primarily rely on the activation of Toll-like receptors (TLRs) for pathogen recognition.

<p>False (B)</p> Signup and view all the answers

Endocytosis and phagocytosis are two interchangeable terms describing the same process of internalizing particles into cells.

<p>False (B)</p> Signup and view all the answers

Superoxide and H2O2 are short-lived molecules that can persist and cause tissue damage.

<p>True (A)</p> Signup and view all the answers

RNIs are long-lived molecules that act with ROIs to give their fullest effect.

<p>False (B)</p> Signup and view all the answers

Catalase, superoxide dismutase, and glutathione are enzymes that contribute to the generation of reactive oxygen intermediates.

<p>False (B)</p> Signup and view all the answers

Reactive Nitrogen Intermediates primarily act through inducible Nitric oxide synthase (iNOS) to exert antimicrobial effects.

<p>True (A)</p> Signup and view all the answers

Neutrophils are less likely to kill ingested microorganisms compared to MC/MFs due to lower respiratory burst.

<p>False (B)</p> Signup and view all the answers

Autophagy and pyroptosis are mechanisms used by pathogens to escape the cytoplasm and avoid detection by PRRs.

<p>False (B)</p> Signup and view all the answers

The phagocyte receptors need to be clustered in order for the phagocyte to undergo cytoskeletal rearrangement during phagocytosis.

<p>True (A)</p> Signup and view all the answers

The ER plays a role in the formation of phagosome membranes and pseudopodia during phagocytosis.

<p>True (A)</p> Signup and view all the answers

Phagocytic and endocytic vesicle membranes are not recycled after phagocytosis.

<p>False (B)</p> Signup and view all the answers

The fusion of lysosomes with the phagosome creates the 'phagolysosome' during phagocytosis.

<p>True (A)</p> Signup and view all the answers

Oxygen-dependent mechanisms play a more significant role than oxygen-independent mechanisms in the process of acidification during phagocytosis.

<p>False (B)</p> Signup and view all the answers

Lysozyme is a key enzyme found within lysosomes that mediates the digestion of gram-positive bacterial cell walls.

<p>True (A)</p> Signup and view all the answers

Prostaglandins are saturated fatty acids derived from arachidonic acid.

<p>False (B)</p> Signup and view all the answers

Leukotrienes are enzymes responsible for the production of chemokines.

<p>False (B)</p> Signup and view all the answers

Histamine acts to decrease vascular permeability.

<p>False (B)</p> Signup and view all the answers

Macrophages secrete adhesion molecules, selectins, and integrins during inflammation.

<p>True (A)</p> Signup and view all the answers

Chemotaxis refers to the movement of white blood cells or fluid from tissues into the lumen of blood vessels.

<p>False (B)</p> Signup and view all the answers

Lymphocyte homing is primarily regulated by prostaglandins.

<p>False (B)</p> Signup and view all the answers

Phagocytic/endocytic barriers are not included in the four main types of defensive barriers/features of innate immunity.

<p>False (B)</p> Signup and view all the answers

During inflammation, the body's immediate defence reaction to infection or damage involves 4 hallmarks: rubor, tumor, calor, and dolor.

<p>True (A)</p> Signup and view all the answers

The Acute Phase Response occurs within 24-48 hours after an inflammatory event.

<p>False (B)</p> Signup and view all the answers

Migration of leukocytes to the site of trauma/infection during inflammation leads to decreased phagocytosis.

<p>False (B)</p> Signup and view all the answers

Opsonins inhibit phagocytosis during inflammation.

<p>False (B)</p> Signup and view all the answers

MEDIATORS released during inflammation do not affect vascular tone and integrity of the endothelial layer.

<p>False (B)</p> Signup and view all the answers

Study Notes

  • Immunity against microbes involves various enzymes and proteins, including acid hydrolases, lipases, neutral proteases, lactoferrin, defensins, cationic proteins, tumor necrosis factor alpha (TNFa), Reactive Oxygen Intermediates (ROIs), and Reactive Nitrogen Intermediates (RNIs).
  • Acid hydrolases include phosphatases, sulphatases, glycosidases, and deoxyribonucleases. Lipases like phospholipase A2. Neutral proteases include collagenases, elastase, and cysteine proteases.
  • Lactoferrin binds to essential nutrients and inhibits bacterial and fungal growth. Defensins are positively charged polypeptides that electrostatically bind to negatively charged PAMPs (pathogen-associated molecular patterns) like LPS and LTA.
  • Cationic proteins, mainly found in neutrophil and eosinophil granules, damage microbial membranes and proteins, and are mostly antibacterial.
  • TNFa is a cytokine secreted mainly by macrophages and neutrophils, which is cytotoxic to tumor cells and activates complement, the classical pathway.
  • Reactive Oxygen Intermediates (ROIs) are generated within professional phagocytes during the respiratory burst and are highly reactive molecules with high potential to damage proteins, lipids, DNA, and cell membranes of microorganisms.
  • Reactive Nitrogen Intermediates (RNIs), such as nitric oxide, are produced by several nitric oxide synthases and play roles in both physiological and pathological conditions.
  • Phagocytes undergo a four-step process of phagocytosis, which includes the stage of 'Exocytosis' where antibodies, lectins/acute phase proteins, complement activation pathways, and proteins are released to enhance microbicidal effects and affect local blood vessels.
  • Inflammation is characterized by the production of various proteins, lipids, and chemicals, including cytokines, chemokines, prostaglandins, leukotrienes, thromboxanes, and histamine.
  • Cytokines, such as interleukin 1, 6, 8, 10, 12, and TNFa, are produced by various cell types and play significant roles in inflammation, including causing local effects and systemic activation.
  • Chemokines are small proteins that act as chemoattractants, stimulating the migration and activation of cells towards the source along a concentration gradient.
  • Prostaglandins, leukotrienes, and thromboxanes are eicosanoids produced from arachidonic acid and act on vascular permeability and leukocyte migration.
  • Histamine increases vascular permeability and smooth muscle contraction.
  • Various adhesion molecules, selectins, and integrins play roles in binding leukocytes to the endothelium and regulating their movement.
  • Chemotaxis is the process of directional movement of cells towards a chemical stimulus.
  • Macrophages are important cells involved in cellular movement during inflammation.
  • Extravasation is the migration of white blood cells or fluid from the lumen of blood vessels into tissues.
  • Overview of inflammation: A complex and multi-step process involving various cells, proteins, and chemical mediators to eliminate pathogens and initiate tissue repair.

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