AIHA and Hypersensitivity Type III Quiz
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Questions and Answers

What does a score of '3+' indicate in reaction scoring?

  • Negative
  • Weak positive
  • Moderate positive
  • Positive but lower titre or avidity than 4+ (correct)

    • What outcome does 'MF' represent in reaction scoring?

  • Some populations positive, some negative (correct)
  • All cell populations are positive
  • All cell populations are negative
  • Moderate positive reaction

    • Which of the following best describes the function of the DAT (Direct anti-globulin test)?

  • Identifies bound antibodies on cell populations (correct)
  • Determines blood type compatibility
  • Measures the overall red blood cell count
  • Assesses hemoglobin levels

    • At what temperature are the tests performed, as indicated in the summary?

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

    Which score indicates a negative result in the reaction scoring system?

    <p>0 (D)</p> Signup and view all the answers

    What is a primary function of the spleen in relation to red blood cells?

    <p>Checking flexibility of red cells (C)</p> Signup and view all the answers

    What type of anaemia results from a drop in the concentration of iron in haemoglobin?

    <p>Iron deficiency anaemia (D)</p> Signup and view all the answers

    Which form of iron is utilized in the body?

    <p>Fe2+ (A)</p> Signup and view all the answers

    What is one potential consequence of iron toxicity?

    <p>Increased risk of bacterial infections (B)</p> Signup and view all the answers

    What role do antibodies play in immune-mediated hemolysis?

    <p>They mark red blood cells for destruction. (B)</p> Signup and view all the answers

    What is a key characteristic of extravascular hemolysis?

    <p>It is mediated by macrophages in the spleen and liver. (D)</p> Signup and view all the answers

    What type of antibodies are developed in response to a patient's own red blood cells?

    <p>Auto-antibodies (D)</p> Signup and view all the answers

    What happens to red blood cells during red cell senescence?

    <p>They lose their ability to deliver oxygen. (D)</p> Signup and view all the answers

    Which of the following conditions is associated with intravascular hemolysis?

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

    Which substance is formed when bilirubin is conjugated?

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

    What is the primary mechanism by which hapten mechanism antibodies cause extravascular hemolysis?

    <p>Adsorption onto red cell surface (D)</p> Signup and view all the answers

    In terms of red blood cell function, what is critical for their flexibility?

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

    In warm autoimmune hemolytic anemia (AIHA), what is the primary location of red cell destruction?

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

    What is a common result of lysis either intravascular or extravascular?

    <p>Decreased hemoglobin concentration (C)</p> Signup and view all the answers

    Which type of antibodies are typically involved in the immune complex mechanism?

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

    What condition may arise due to the destruction of red cells in the context of hemolytic anemia?

    <p>Disseminated intravascular coagulation (DIC) (B)</p> Signup and view all the answers

    What laboratory finding is typically positive in cases of immune-mediated hemolysis?

    <p>Positive Coombs test (B)</p> Signup and view all the answers

    What symptom is NOT typically associated with immune-mediated hemolytic anemia?

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

    Which drug is known to potentially cause immune hemolytic anemia via the drug adsorption mechanism?

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

    Which process primarily leads to the extravascular destruction of red cells in vivo?

    <p>Phagocytosis by macrophages (D)</p> Signup and view all the answers

    What is the primary factor that prevents bilirubin toxicity during transport after red cell hemolysis?

    <p>Binding to albumin (C)</p> Signup and view all the answers

    During which stage of erythropoiesis does cell repair cease?

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

    How long do circulating red cells typically live in the human body?

    <p>3-4 months (B)</p> Signup and view all the answers

    What is the main pathway for iron re-absorption in the body?

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

    Which of the following is NOT a sign of immune mediated hemolytic anemia?

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

    Which immune response is primarily responsible for alloimmune hemolytic reactions?

    <p>Antibody-mediated response (D)</p> Signup and view all the answers

    What laboratory test is commonly used to detect immune mediated hemolysis?

    <p>Direct Coombs test (A)</p> Signup and view all the answers

    What laboratory finding indicates a hapten immune mechanism is probably involved in haemolysis?

    <p>Positive direct antiglobulin test (D)</p> Signup and view all the answers

    What describes the action of cephalothin in haemolytic processes?

    <p>It results in non-specific attachment of proteins to red cell membranes. (A)</p> Signup and view all the answers

    What laboratory investigation would provide a positive result if a drug has modified red cell membranes?

    <p>Incubation of drug, serum, and reagent cells together (D)</p> Signup and view all the answers

    Which test is used to detect free antibodies in patient plasma?

    <p>Indirect globulin test (IAT) (B)</p> Signup and view all the answers

    Which of the following is NOT generally associated with a haemolytic process?

    <p>Presence of circulating antibodies (A)</p> Signup and view all the answers

    What could be implied by finding an unexpected positive DAT in a laboratory test?

    <p>Drug-induced modification of red cells could be present. (D)</p> Signup and view all the answers

    In the context of immune-mediated hemolysis, what does a positive indirect antiglobulin test (IAT) indicate?

    <p>Existence of free antibodies in serum. (C)</p> Signup and view all the answers

    Which outcome is expected when drug-induced membrane modification occurs in red blood cells?

    <p>Unexpected positive DAT with no detected antibodies. (D)</p> Signup and view all the answers

    What is the primary focus of interpreting antigrams in relation to immune hemolysis?

    <p>To establish generalized reaction patterns indicating certain disease states. (A)</p> Signup and view all the answers

    Which of the following statements about different types of immune-mediated hemolysis is accurate?

    <p>Some mechanisms are associated with drug modifications of red cell membranes. (B)</p> Signup and view all the answers

    Study Notes

    AIHA and Hypersensitivity type III

    • AIHA refers to autoimmune hemolytic anemia
    • Hypersensitivity type III is a key component in the presentation of AIHA
    • The presentation covers the normal development of red blood cells and their circulation
    • It also covers different types of immune-mediated hemolytic reactions and how they can be detected via lab tests
    • Specific learning objectives aim to explain red blood cell development and how it relates to intra and extra vascular destruction
    • Understanding different immune hemolysis types and contrasting results from varied immune-mediated hemolytic reactions are also key objectives

    Contents

    • Normal red blood cell function, iron absorption, and re-absorption are detailed
    • Pathology, pathophysiology, and signs/symptoms are discussed
    • Laboratory interpretation of tests, with an emphasis on how blood samples may affect results, is explored

    Normal Function of Red Blood Cells, Iron Absorption, and Re-absorption

    • Red blood cell life cycle (including erythropoiesis)
    • Iron absorption and re-absorption processes
    • Iron toxicity and movement within the blood

    Immune Haemolytic Anaemias

    • Immune-mediated hemolytic reactions create specific and nonspecific patterns
    • Specific antibodies are generated in relation to particular antigens
    • Different types and forms of hemolysis are mediated by various antibodies
    • Different drugs can interact with red blood cells, forming immune complexes and causing haemolysis

    Immune Haemolytic Anaemia – Antibody Types

    • Allo-antibodies (type II) are developed in response to other persons' cells
      • Can be triggered by pregnancy or transfusions (immediate or delayed reactions)
    • Auto-antibodies (type II) are developed against the patient's own red cells
      • Can be primary (idiopathic) or secondary (due to malignancy or viral infection)
    • Antibodies formed against drugs (type III) are developed due to exposure to specific drugs
      • This can lead to the creation of novel antigens

    Warm or Cold AIHA

    • Warm AIHA (IgG): extravascular haemolysis (destruction outside blood vessels)
      • IgG binds at 37°C (body temperature)
      • Gets removed by liver and spleen leading to bilirubin release
    • Cold AIHA (IgM): intravascular haemolysis (destruction inside blood vessels)
      • IgM antibodies are activated at cooler temperatures
      • Results in hemoglobin release into the vascular system

    Pathogenesis and Physiology

    • Transfusion with incompatible blood can lead to B-cell/plasma cell derangement (e.g., myeloma/EBV infection)
    • Familial predisposition can play a role in autoimmune disease conditions
    • Complement-mediated destruction of red blood cells (IgG:C3b, IgM:MAC) is possible
    • Intravascular hemolysis may lead to haemolysed blood, risk of disseminated intravascular coagulation (DIC), haemoglobinemia, and haemoglobinuria
    • Extravascular hemolysis can cause jaundice, hepatosplenomegaly, and icterus

    Patient Presentation

    • Identical symptoms of immune-mediated hemolytic reactions include anaemia, pallor, and shortness of breath
    • Different symptoms include jaundice and haemoglobinuria

    Drug Adsorption Mechanism

    • Hapten mechanism: drugs/metabolites adsorb onto red blood cell surfaces
    • This leads to the production of drug-specific IgG alloantibodies
    • Antibodies attach to drug coatings on red blood cells
    • Extravascular haemolysis can result
    • Lab findings often include a positive DAT (direct antiglobulin test)

    Immune Complex Mechanism

    • Anti-drug alloantibodies (IgM) bind to drugs in circulation
    • Immune complexes attach to red blood cells
    • Complement activation follows, leading to intravascular or extravascular haemolysis
    • Can be severe/fatal, and can lead to 'innocent bystander' destruction; e.g., quinine, cephalosporins

    Immune Complex Mechanism (Lab Findings)

    • Hapten immune mechanism likely involved
    • DAT positive test
    • No antibodies detected in the lab investigation
    • Positive results from incubating drug, serum, and reagent cells together

    Membrane Modification Mechanism

    • Drugs modify red blood cell membranes, leading to non-specific protein attachments
    • This rarely causes haemolysis (e.g., cephalosporin)

    Summary

    • Defining different types of immune-mediated haemolysis
    • Understanding how various antibodies modulate and mediate hemolysis
    • Examining how specific drugs interact with red blood cells and cause immune complex-mediated haemolysis
    • Investigating how sample presentation may affect testing results
    • Diagnosing conditions via specific and non-specific antigram patterns are indicated

    Laboratory Interpretation of Tests

    • Understanding how sample presentation might affect test results
    • Interpreting antigrams to identify specific antigens or underlying conditions
    • Differentiating between IATs (indirect antiglobulin tests) and DATs (direct antiglobulin tests) for immune hemolysis diagnosis

    How the Test Work

    • IAT: Detects free antibodies in patient plasma using known red blood cells
    • DAT: Identifies antibodies bound to red blood cells using known reagents

    Reaction Scoring

    • Scoring results of tests performed for different reactions to quantify the severity and type of reaction

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    AIHA and Hypersensitivity type III PDF

    Description

    This quiz focuses on Autoimmune Hemolytic Anemia (AIHA) and the role of Hypersensitivity Type III in its presentation. It covers the development of red blood cells, immune-mediated hemolytic reactions, and the related laboratory tests. Key learning objectives include understanding red blood cell function, pathology, and test interpretation.

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