Autoimmune hemolytic anemia

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    • Immunohemolytic Anemia
      • Antibodies bind to red cells, leading to their premature destruction.
      • Diagnosis requires the detection of antibodies and/or complement on red cells from the patient
      • direct Coombs antiglobulin test
        • patient’s red cells are mixed with sera containing antibodies that are specific for human immunoglobulin or complement. (MCQ)
        • If either immunoglobulin or complement is present on the surface of the red cells, the multivalent antibodies cause agglutination, which is easily appreciated visually as clumping.
      • indirect Coombs antiglobulin test
        • patient’s serum is tested for its ability to agglutinate commercially available red cells bearing particular defined antigens
        • This test is used to characterize the
          • antigen target
          • temperature dependence of the responsible antibody
      • Warm Antibody Type.
        • This is the most common form of immunohemolytic anemia(MCQ)
        • About 50% of cases are idiopathic (primary); (MCQ)
        • Most causative antibodies are of the IgG class; less commonly, IgA (MCQ)
        • The red cell hemolysis is mostly extravascular(MCQ)
        • IgG-coated red cells bind to Fc receptors on phagocytes, which remove red cell membrane during “partial” phagocytosis.
        • the loss of membrane converts the red cells to spherocytes, which are sequestered and removed in the spleen.
        • Moderate splenomegaly due to hyperplasia of splenic phagocytes is usually seen. (MCQ)
        • Antigenic drugs.
          • hemolysis usually follows large, intravenous doses of the offending drug occurs 1 to 2 weeks after therapy is initiated
          • Seen in penicillin and cephalosporinsquinidine(MCQ)
        • Tolerance-breaking drugs(MCQ)
          • α-methyldopa is the prototype
          • produce of antibodies against red cell antigens, particularly the Rh blood group antigens.
    • Cold Agglutinin Type immunohemolytic anemia
      • caused by IgM antibodies (MCQ)
      • bind red cells avidly at low temperatures (0°–4°C) (MCQ)
      • they  appear transiently following certain infections, such as with (MCQ)
        • Mycoplasma pneumonia
        • Epstein-Barr virus
        • cytomegalovirus, influenza virus
        • human immunodeficiency virus (HIV).
      • In these settings the disorder is self-limited
      • antibodies rarely induce clinically important hemolysis.
      • Chronic cold agglutinin immunohemolytic anemia occurs in association with certain B-cell neoplasms or as an idiopathic condition. (MCQ)
        • more difficult to treat unlike antibody immunohemolytic anemia
      • Vascular obstruction caused by agglutinated red cells results in pallor, cyanosis, and Raynaud phenomenon in body parts exposed to cold temperature. (MCQ)
    • Cold Hemolysin Type.
      • Cold hemolysins
        • autoantibodies responsible for an unusual entity known as paroxysmal cold hemoglobinuria.
        • causes substantial, sometimes fatal, intravascular hemolysis and hemoglobinuria. (MCQ)
        • The autoantibodies are IgGs (MCQ)
        • IgGs bind to the P blood group antigen on the red cell surface in cool, peripheral regions of the body. (MCQ)
        • Complement-mediated lysis occurs when the cells recirculate to warm central regions, since the complement cascade functions more efficiently at 37°C. (MCQ)
      • Most cases are seen in children following viral infections; in this setting the disorder is transient, and most of those affected recover within 1 month.
    • Hemolytic Anemia Resulting from Trauma to Red Cells
      • seen in individuals with cardiac valve prostheses
      • Artificial mechanical cardiac valves are more frequently implicated than are bioprosthetic porcine valves(MCQ)
      • Microangiopathic hemolytic anemia
      • Causes (MCQ)
        • most commonly seen with disseminated intravascular coagulation
        • thrombotic thrombocytopenic purpura (TTP)
        • hemolytic-uremic syndrome (HUS)
        • malignant hypertension
        • systemic lupus erythematosus,
        • disseminated cancer.
      • The common pathogenic feature in these disorders is a microvascular lesion that results in luminal narrowing, often due to the deposition of fibrin and platelets.
      • These vascular changes produce shear stresses that mechanically injure passing red cells
      • . Regardless of the cause, traumatic damage leads to the appearance of (MCQ)
        • red cell fragments (schistocytes),
        • “burr cells,”
        • “helmet cells,”
        • “triangle cells” in blood smears


    Hemolytic Anemia
    WAHA Warm Autoimmune Hemolytic Anemia AIHA
    Hemolytic Anemia
    Cold Agglutinin Disease (autoimmune hemolytic anemia: Mycoplasma Pneumoniae & Mononucleosis)