Immunology: Antibody Functions and Mechanisms
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Questions and Answers

What type of cell primarily produces antibodies in the immune response?

  • T cells
  • Mast cells
  • Macrophages
  • B cells (correct)
  • Which property describes the specific nature of antibodies in recognizing antigens?

  • Broad specificity
  • Low affinity
  • Low molecular weight
  • High order of specificity (correct)
  • What is the molecular weight characteristic of antibodies?

  • Variable molecular weight
  • No defined molecular weight
  • High molecular weight (correct)
  • Low molecular weight
  • Which immunoglobulin is more effective for agglutination of antigens?

    <p>IgM</p> Signup and view all the answers

    Where do B cells mature before migrating to lymphoid organs?

    <p>Bone marrow</p> Signup and view all the answers

    What happens to B cells after they encounter their specific antigen?

    <p>They divide into many clones</p> Signup and view all the answers

    What is the fate of the specific antibody once it enters circulation?

    <p>It helps direct further synthesis</p> Signup and view all the answers

    Which of the following fluids can antibodies be found in?

    <p>Serum, saliva, and seminal fluid</p> Signup and view all the answers

    What is the role of opsonization in the immune response?

    <p>To make an antigen more susceptible to phagocytosis</p> Signup and view all the answers

    What is the primary difference between kappa and lambda light chains?

    <p>They have different amino acid sequences and antigenic properties</p> Signup and view all the answers

    What is the molecular weight range for immunoglobulin light chains?

    <p>25,000 - 30,000 Daltons</p> Signup and view all the answers

    What type of immune response involves the neutralization of viruses by antibodies?

    <p>Neutralization</p> Signup and view all the answers

    Which statement best describes the process of antigen-antibody interaction?

    <p>A specific antibody will only have one type of light chain</p> Signup and view all the answers

    Which immunoglobulin is primarily responsible for triggering the complement system?

    <p>IgM</p> Signup and view all the answers

    What is one potential negative outcome of inflammation in the immune response?

    <p>Contributing to chronic inflammatory conditions</p> Signup and view all the answers

    Which of the following best describes how antibody-dependent cell-mediated cytotoxicity functions?

    <p>Antibodies coat target organisms and attract non-specific immune cells</p> Signup and view all the answers

    What is the sedimentation coefficient for IgM?

    <p>19 S</p> Signup and view all the answers

    Which immunoglobulin has the highest molecular weight?

    <p>IgM</p> Signup and view all the answers

    Which type of antibodies react at a temperature of 4 degrees Celsius?

    <p>Cold antibodies</p> Signup and view all the answers

    What is the main function of agglutinins?

    <p>Induce cell clumping</p> Signup and view all the answers

    Which molecular weight corresponds to IgA2?

    <p>350,000</p> Signup and view all the answers

    Isoantibodies are produced after the introduction of antigens from which source?

    <p>The same species</p> Signup and view all the answers

    What is the primary role of opsonins in immune response?

    <p>Enhance phagocytosis</p> Signup and view all the answers

    Which type of antibodies are described by their ability to react with antigens from another species?

    <p>Heterophile antibodies</p> Signup and view all the answers

    What temperature do warm antibodies typically react at?

    <p>37 degrees Celsius</p> Signup and view all the answers

    Which agglutinins are modified to no longer cause agglutination?

    <p>Agglutinoids</p> Signup and view all the answers

    What type of antibody is IgE classified as?

    <p>Incomplete antibody</p> Signup and view all the answers

    Which immunoglobulin exhibits a sedimentation coefficient of 7 S?

    <p>IgG</p> Signup and view all the answers

    What is the primary function of precipitin antibodies?

    <p>Forming complexes with antigens</p> Signup and view all the answers

    Which of the following is NOT a characteristic of hemagglutinins?

    <p>Act upon bacterial cells</p> Signup and view all the answers

    Which immunoglobulin is primarily responsible for fighting against parasitic infections?

    <p>IgE</p> Signup and view all the answers

    What is a significant effect of elastase release in the lungs?

    <p>It digests the alveolar sac.</p> Signup and view all the answers

    What condition is associated with a deficiency of alpha-1 antitrypsin?

    <p>Emphysema</p> Signup and view all the answers

    How does haptoglobin function in relation to hemoglobin?

    <p>It prevents hemoglobin loss into urine.</p> Signup and view all the answers

    What genetic disorder is characterized by copper metabolism issues and may cause corneal deposits?

    <p>Wilson’s disease</p> Signup and view all the answers

    Which pathway of the complement system is activated by antigen-antibody complexes?

    <p>Classical pathway</p> Signup and view all the answers

    What is the primary role of ceruloplasmin in the body?

    <p>To bind copper and transport it.</p> Signup and view all the answers

    Which condition may lead to diminished levels of haptoglobin?

    <p>Hemolytic transfusion reactions</p> Signup and view all the answers

    Kayser-Fleischer rings are associated with which disorder?

    <p>Wilson’s disease</p> Signup and view all the answers

    What is the role of interleukin-1 beta in the immune response?

    <p>Induces fever and activates phagocytes</p> Signup and view all the answers

    Which cytokine primarily acts as a cell growth factor for T cells?

    <p>Interleukin-2</p> Signup and view all the answers

    What can be a consequence of a cytokine storm?

    <p>Shock and multiorgan failure</p> Signup and view all the answers

    What is the function of IL-1 receptor antagonist (IL-1RA)?

    <p>To prevent IL-1 from exerting inflammatory effects</p> Signup and view all the answers

    How are interleukins currently numbered?

    <p>From IL-1 to IL-32</p> Signup and view all the answers

    What does IL-6 stimulate in the immune response?

    <p>Production of acute-phase proteins</p> Signup and view all the answers

    Which characteristic best describes the function of cytokines?

    <p>Induce the movement of cells for immunological functions</p> Signup and view all the answers

    Which type of microorganisms can induce the production of cytokines?

    <p>Bacterial lipopolysaccharides and flagella from motile microorganisms</p> Signup and view all the answers

    What role does alpha-1 antitrypsin (AAT) play in the immune system?

    <p>Inhibits the action of proteases produced by neutrophils</p> Signup and view all the answers

    What is a significant consequence of alpha-1 antitrypsin deficiency?

    <p>Premature emphysema due to unchecked WBC activity</p> Signup and view all the answers

    What is the primary function of serum amyloid A?

    <p>Facilitates the removal of cholesterol from tissues</p> Signup and view all the answers

    Which factor is primarily responsible for the elevation of C-reactive protein (CRP) during inflammation?

    <p>Increased levels of cytokines like IL-6</p> Signup and view all the answers

    How does alpha-1 antitrypsin deficiency affect lung function over time?

    <p>Leads to alveolar wall destruction and emphysema</p> Signup and view all the answers

    Which condition is primarily linked to elevated levels of C-reactive protein?

    <p>Acute myocardial infarction</p> Signup and view all the answers

    What complication arises from the buildup of white blood cells in the context of AAT deficiency?

    <p>Formation of atherosclerotic plaques</p> Signup and view all the answers

    In what way does the complement system interact with C-reactive protein?

    <p>CRP binds to bacteria and activates complement</p> Signup and view all the answers

    What pathology is primarily caused by the continuous release of elastase by white blood cells?

    <p>Emphysema</p> Signup and view all the answers

    What happens when there is a deficiency of alpha-1 antitrypsin (AAT) in the body?

    <p>Risk of early emphysema development</p> Signup and view all the answers

    What role does haptoglobin play in hemolytic disorders?

    <p>Binds free hemoglobin to prevent loss into urine</p> Signup and view all the answers

    Which condition is indicated by low levels of haptoglobin in the blood?

    <p>Hemolytic transfusion reactions</p> Signup and view all the answers

    Which protein is primarily responsible for copper binding and may indicate Wilson's disease when deficient?

    <p>Ceruloplasmin</p> Signup and view all the answers

    What is a major characteristic of Kayser-Fleischer rings?

    <p>They are copper deposits in the cornea.</p> Signup and view all the answers

    Which pathway of the complement system is activated by microbial surfaces?

    <p>Alternative pathway</p> Signup and view all the answers

    Which factor in plasma is most abundant and crucial for preventing bleeding disorders?

    <p>Fibrinogen</p> Signup and view all the answers

    What is the significance of a C-Reactive Protein (CRP) level greater than 2 mg/dl in individuals?

    <p>It signifies high cardiovascular risk.</p> Signup and view all the answers

    Which function does C-Reactive Protein predominantly serve in the body?

    <p>Opsonization of pathogens.</p> Signup and view all the answers

    What is a significant consequence of alpha-1 antitrypsin (AAT) deficiency?

    <p>Increased inflammation in the lungs.</p> Signup and view all the answers

    How does alpha-1 antitrypsin function in the respiratory tract?

    <p>It neutralizes enzymes to prevent lung tissue damage.</p> Signup and view all the answers

    Which acute phase reactant is primarily produced in response to tissue injury and infection?

    <p>C-Reactive Protein.</p> Signup and view all the answers

    What is the role of serum amyloid A in inflammation?

    <p>Transfers cholesterol from macrophages at sites of injury.</p> Signup and view all the answers

    What can excessive release of elastase cause in the lungs?

    <p>Destruction of alveolar structures.</p> Signup and view all the answers

    Which condition is linked to increased C-Reactive Protein levels due to inflammation?

    <p>Coronary Heart Disease.</p> Signup and view all the answers

    What is one of the functions of interleukin-6 in the immune response?

    <p>Promotes the differentiation of B cells into plasma cells</p> Signup and view all the answers

    Which cytokine is primarily responsible for inducing fever during an immune response?

    <p>Interleukin-1 beta</p> Signup and view all the answers

    What significant consequence can result from a cytokine storm?

    <p>Shock and multiorgan failure</p> Signup and view all the answers

    What is the primary role of haptoglobin in the body?

    <p>Binding free hemoglobin to prevent kidney damage</p> Signup and view all the answers

    What is a common outcome of alpha-1 antitrypsin deficiency?

    <p>Increased risk of emphysema</p> Signup and view all the answers

    Which interleukin serves as a cell growth factor specifically for T cells?

    <p>Interleukin-2</p> Signup and view all the answers

    What condition may lead to lower levels of haptoglobin in the blood?

    <p>Hemolytic disorders</p> Signup and view all the answers

    What characterizes the pathophysiology of emphysema related to alpha-1 antitrypsin deficiency?

    <p>Loss of elasticity in lung tissue</p> Signup and view all the answers

    Study Notes

    Hemagglutination

    • Red blood cell agglutination used to determine ABO blood types and detect influenza and measles viruses.

    Opsonization

    • Antibodies coat antigens, enhancing their ingestion and lysis by phagocytic cells.

    Neutralization

    • IgG inactivates viruses by binding to their surface, and toxins are neutralized by blocking their active sites.

    Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)

    • Destroys large organisms like worms.
    • The target organism is coated with antibodies and bombarded with chemicals from non-specific immune cells.

    Inflammation

    • Essential for fighting infections and healing tissues.
    • Can contribute to chronic inflammatory conditions.

    Activation of Complement

    • IgG and IgM trigger the complement system, resulting in cell lysis and inflammation.

    Antibody Structure/Immunoglobulins

    • Gerald Edelman and Rodney Porter:
      • Worked with IgG.
      • Edelman used analytical centrifugation.
      • Porter used the enzyme papain.
    • Basic Structural Unit:
      • Four polypeptide chains (2 heavy chains, 2 light chains) linked by disulfide bonds.
    • Key Fact: One virus or microbe can have several antigenic determinant sites or epitopes to which different antibodies may bind.
    • Light Chains:
      • Small chains common to all immunoglobulins.
      • Molecular Weight: 25,000 Daltons.
      • 200-220 amino acids.
      • Two subtypes: kappa and lambda.
      • Kappa and Lambda have different amino acid sequences and are antigenically different.
      • About 65% of immunoglobulin molecules have Kappa chains, whereas 35% have Lambda chains.
      • One antibody has only one type of light chain, never both.
    • Paratope:
      • Region on the antibody reacting to the epitope of an antigen.
    • Clonal Selection Process:
      • Individual lymphocytes are genetically pre-programmed to produce one type of immunoglobulin.
      • A specific antigen finds or selects those particular cells capable of responding to it, causing them to proliferate.
    • B Cell Production of Antibodies:
      • B cells develop from stem cells in the bone marrow.
      • After maturation, they migrate to lymphoid organs (lymph nodes, spleen).
      • When a B cell encounters an antigen, it is stimulated and divides into plasma cells, which secrete antibodies.

    Properties of Antibodies

    • Protein in nature
    • High molecular weight
    • Found in serum/plasma, CSF, saliva, seminal fluid.
    • Possess high order of specificity

    Agglutination

    • Antibodies cause antigens to clump together.
    • IgM is more effective than IgG in agglutination.

    Svedberg Unit

    • Indicates the sedimentation rate in an analytical ultracentrifuge.

    Immunoglobulin Classes

    • Sedimentation Coefficient | Molecular Weight
      • IgG | 7S, 150,000
      • IgA | 7S, 160,000 (IgA1), 350,000 (IgA2)
      • IgM | 19S, 900,000
      • IgD | 7S, 180,000
      • IgE | 8S, 190,000

    Antibody Classification

    • According to Temperature
      • Cold Antibodies: Reacts at 4°C (room temperature).
      • Warm Antibodies: Reacts at 37°C (Rh antibodies).
    • According to Occurrence
      • Natural Antibodies: Appear without any apparent stimulus (e.g., anti-A and anti-B antibodies).
      • Immune Antibodies: Appear following the introduction of an antigen.
    • According to Species That Produce Them
      • Isoantibodies: Antibodies produced after the introduction of the antigen from the same species.
      • Heterophile Antibodies: Antibodies produced after the introduction of the antigen from another species.
    • According to Reaction with an Antigen
      • Immobilization of Motile Organisms
      • Agglutinins: Antibodies responsible for the immobilization of motile organisms and cell clumping.
      • Precipitins: Antibodies that cause precipitate formation by forming complexes with antigen molecules in solution.
      • Agglutinoids: Agglutinins modified by heat, losing their ability to agglutinate but still capable of combining with specific agglutinogens.
      • Hemagglutinins: Cause agglutination of RBCs.
      • Lysins: Cause dissolution of antigenic cells.
        • Bacteriolysin: Acts upon bacterial cells.
        • Hemolysin: Acts upon RBCs.
        • Leucocidin: Kills leukocytes with or without lysis.
    • According to In-Vitro Behavior
      • Opsonin: Acts on bacterial invaders, weakening their resistance to phagocytosis by leukocytes.
    • Point of Differentiation | Complete Antibody | Incomplete Antibody
      • Complete Antibody: Can agglutinate cells directly.
      • Incomplete Antibody: Cannot agglutinate cells directly, but can bind to antigens.

    Emphysema

    • Emphysema is a lung disease characterized by the breakdown of the alveoli (tiny air sacs in the lungs).
    • It is caused by the release of elastase by white blood cells (WBCs) which breaks down the alveolar tissue.
    • Alpha-1 antitrypsin (AAT) is a protein that normally inhibits elastase, preventing the destruction of the alveoli.
    • A deficiency in AAT can lead to premature emphysema.

    Alpha-1 Antitrypsin (AAT)

    • AAT is a protease inhibitor that specifically targets elastase, an enzyme released from leukocytes during bacterial activity.
    • AAT deficiency can lead to premature emphysema.
    • In AAT deficiency, WBCs are not inhibited from releasing elastase, which can lead to the breakdown of the alveoli.

    Haptoglobin

    • Haptoglobin is a protein that binds to free hemoglobin in the bloodstream.
    • It prevents the loss of hemoglobin and its constituent iron into the urine.
    • Haptoglobin is used to evaluate the degree of hemolytic transfusion reactions and hemolytic disease of the newborn.
    • Low levels of haptoglobin may indicate hemolysis (breakdown of red blood cells).

    Ceruloplasmin

    • Ceruloplasmin is a copper-binding protein that has enzymatic activities.
    • It imparts a blue color to plasma and is a marker for Wilson's disease.

    Wilson's Disease

    • Wilson's disease is an autosomal recessive inherited disorder in copper metabolism.
    • It results in copper deposition in the cornea, skin, liver, and brain.
    • Kayser-Fleischer rings are copper deposits in the cornea, a characteristic symptom of Wilson's disease.

    Menkes Kinky Hair Syndrome

    • Menkes kinky hair syndrome is a copper metabolism disorder.
    • It is characterized by kinky hair, due to a deficiency in copper.

    Complement C3

    • Complement C3 is the most abundant complement protein in serum.
    • It plays a crucial role in the immune system.
    • Complement C3 is activated through three pathways:
      • Classical pathway: Activated by antigen-antibody complexes.
      • Alternative pathway: Activated by microbial surfaces and other foreign substances.
      • Mannose-binding lectin pathway: Activated by mannose-binding lectin, a protein that binds to carbohydrates on the surface of microorganisms.

    Cytokines

    • Cytokines are small soluble proteins that regulate the immune system.
    • They are produced by cells of the immune system in response to stimuli, such as bacterial products or foreign antigens.
    • Cytokines induce the movement of cells or their immunological function.
    • A cytokine storm is a massive overproduction and dysregulation of cytokines, leading to shock, multi-organ failure, and even death.

    Interleukins

    • Interleukins are a family of cytokines that mediate communication between white blood cells (WBCs).
    • They are numbered from IL1 to IL32.

    Interleukin 1

    • Interleukin 1 (IL-1) is a family of cytokines that consists of IL-1 alpha, IL-1 beta, and IL-1 RA (receptor antagonist).
    • IL-1 alpha: Remains intracellular within monocytes and macrophages, released only after cellular death. It attracts inflammatory cells to the site of infection.
    • IL-1 beta: Is cleaved intracellularly and then secreted by monocytes. It induces fever, activation of phagocytes, and production of acute-phase reactants.
    • IL-1RA: Competitively binds to the IL-1 receptor, preventing IL-1 from exerting its inflammatory effects.

    Interleukin 2

    • Interleukin 2 (IL-2) is a T cell growth factor that stimulates the growth and division of T cells, allowing for rapid expansion of the immune response.

    Interleukin 6

    • Interleukin 6 (IL-6) stimulates the production of acute-phase proteins and promotes the differentiation of B cells into plasma cells.

    Acute Phase Reactants

    • Acute phase reactants are proteins produced by the liver in response to inflammation, infection, or injury.
    • They are produced within 12-24 hours in response to increased cytokine levels.

    C-Reactive Protein (CRP)

    • CRP is a positive acute-phase reactant.
    • It is a ring-shaped protein composed of five identical subunits.
    • CRP functions in opsonization, complement activation, and inflammation.
    • It is a marker for pneumococcal infection and is used to assess cardiovascular risk.

    Serum Amyloid A

    • Serum amyloid A is an apolipoprotein synthesized in the liver.
    • It is associated with HDL (high-density lipoprotein) cholesterol and removes cholesterol from cholesterol-filled macrophages at the site of injury.

    Emphysema

    • Emphysema is a lung condition where the alveolar sacs, or respiratory tract, are digested by elastase, an enzyme released by white blood cells (WBCs).
    • This digestion process leads to the destruction of lung tissue, making it difficult to breathe.
    • Alpha-1 antitrypsin (AAT) is a protein that inhibits elastase, preventing it from destroying lung tissue.
    • A deficiency in AAT can result in premature emphysema.

    Fibrinogen

    • Fibrinogen is the most abundant coagulation factor found in plasma.
    • It's produced in the liver and prevents bleeding disorders.
    • When converted to fibrin, it forms a mesh-like structure that helps to stop bleeding.

    Haptoglobin

    • Haptoglobin binds to free hemoglobin, preventing its loss into the urine.
    • Hemoglobin is nephrotoxic (toxic to the kidneys) and causes a range of health problems if not controlled.
    • Low levels of haptoglobin may indicate a severe hemolytic transfusion reaction or hemolytic disease of the newborn.

    Ceruloplasmin

    • Ceruloplasmin is a copper-binding protein with enzymatic activity.
    • It imparts a blue color to the protein and serves as a marker for Wilson's disease, an autosomal recessive disorder affecting copper metabolism.
    • Wilson's disease leads to copper deposition in the cornea, skin, liver, and brain.

    Kayser-Fleischer Rings

    • Copper deposits in the cornea of patients with Wilson's disease can form rings, known as Kayser-Fleischer rings. These rings are a characteristic symptom of the disease.

    Menkes Kinky Hair Syndrome

    • Menkes kinky hair syndrome is another copper metabolism disorder.
    • It results in abnormally curled hair due to problems with copper metabolism.

    Complement C3

    • Complement C3 is the most abundant complement protein found in serum. Involved in the following pathways:
      • Classical Pathway: Activated by antigen-antibody complexes
      • Alternative Pathway: Activated by microbial surfaces and foreign substances.
      • Mannose-Binding Lectin Pathway: Activated by mannose-binding lectin, a protein that binds to carbohydrates on the surface of microorganisms.

    7 Acute Phase Reactants

    • Acute phase reactants are proteins produced by the liver in response to inflammation, infection, or injury.
    • They are produced within 12-24 hours after an increase in cytokines, such as Interleukin 1 beta, Interleukin 6, and Tumor Necrosis Factor (TNF alpha), which are produced by monocytes and macrophages at the site of inflammation.

    C-Reactive Protein (CRP)

    • CRP is a positive acute phase reactant that is ring-shaped and composed of five identical subunits.
    • It plays a role in opsonization, complement activation, and inflammation.
    • CRP is a marker for pneumococcal infection, as it precipitates with C-substance derived from the polysaccharide of bacteria.
    • It is an early marker for individuals at risk for coronary heart disease. It binds to atherosclerotic plaques.
    • High CRP levels (greater than 2mg/dl) are associated with a significant risk for cardiovascular disease.

    Serum Amyloid A (SAA)

    • SAA is an apolipoprotein synthesized in the liver.
    • It is associated with HDL (high-density lipoprotein) cholesterol and helps to remove cholesterol from cholesterol-filled macrophages at the site of injury.

    Alpha-1 Antitrypsin (AAT)

    • AAT is a major component of the alpha-1 band of serum electrophoresis.
    • It acts as a protease inhibitor, specifically for elastase.
    • AAT prevents the constant release of digestive enzymes by WBCs after an infection has been neutralized.
    • AAT deficiency can lead to premature emphysema.

    Cytokines

    • Cytokines are small soluble proteins that regulate the immune system.
    • They are produced in response to various stimuli, such as bacterial lipopolysaccharides, flagella of some motile microorganisms, and other products of microorganisms.
    • Cytokines regulate leukocyte activity and contribute to the elimination of infection.

    Cytokine Storm

    • A cytokine storm is a massive overproduction and dysregulation of cytokines, leading to shock, multiorgan failure, and even death.

    Interleukins (ILs)

    • Interleukins are soluble substances that allow communication between white blood cells (WBCs).
    • They are numbered from IL1 to IL32.

    Interleukin 1 (IL-1)

    • IL-1 is a family that includes IL-1 alpha, IL-1 beta, and IL-1RA (receptor antagonist). - IL-1 alpha: Remains intracellular within monocytes and macrophages and can only be released after cellular death. - IL-1 beta: Cleaved intracellularly and then secreted by monocytes. It induces fever, activation of phagocytes, and production of acute phase reactants. - IL-1RA: Competitively binds to the IL-1 receptor, preventing IL-1 from exerting its inflammatory effects.

    Interleukin 2 (IL-2)

    • IL-2 is a T cell growth factor that stimulates the growth and division of T cells, allowing for a rapid expansion of the immune response.

    Interleukin 6 (IL-6)

    • IL-6 stimulates the production of acute-phase proteins, promotes the differentiation of B cells into plasma cells, and promotes the production of neutrophils.

    Tumor Necrosis Factor (TNF)

    • TNF is a cytotoxic agent that targets tumor cells and virally infected cells.
      • Tumor Necrosis Factor Alpha (TNF alpha): The most prominent member of the TNF family, with diverse biological functions.

    Hot T-Bone Steak

    • A mnemonic to remember the major cytokines:
      • IL-1
      • IL-2
      • IL-6
      • TNF

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