1. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Immune Hemolytic Anemia 2. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Introduction Immune hemolytic anemia (IHA) RBCs destroyed prematurely by immune process mediated by antibody and/or complement Presence and severity of anemia depends on: Severity of hemolysis Ability of BM to compensate for RBC loss continued on next slide 3. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Introduction Immune hemolytic anemia (IHA) Initial confirmation of immune mechanism Demonstration of attachment of Ab or complement to RBCs of patient Diagnosis of anemia: Hb and Hct, reticulocytes and/or unconjugated bilirubin, haptoglobin 4. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Classification of IHAs Based on stimulus for antibody production Autoimmune hemolytic anemia Drug-induced hemolytic anemia Alloimmune hemolytic anemia Important to determine process because each type requires specific treatment 5. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Classification Autoimmune hemolytic anemia (AIHA) Shortened RBC survival Caused by production of autoantibodies against RBC antigens Ab-induced reactions include Sensitization, agglutination, hemolysis continued on next slide 6. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Classification Autoimmune hemolytic anemia (AIHA) Further classified Warm-antibody autoimmune HA (WAIHA) Cold-antibody AIHA (cold agglutinin disease/CAD) Mixed-type AIHA (both warm-reacting and cold-reacting autoantibodies) 7. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-1 Classification of Immune Hemolytic Anemias 8. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-2 Characteristics of Agglutinins in Hemolytic Anemia 9. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Classification Drug-induced hemolytic anemia Drugs attach to RBC membrane or alter it. Classified based on reactions of patient's RBCs and drug in vitro test system Drug-dependent Drug-independent 10. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Classification Alloimmune hemolytic anemia Antibody (Ab) development to RBC antigen (Ag) that individual lacks Do not react with individual's own RBCs HDFN-mother makes Abs against Ags on fetal RBCs Transfusion reactions where recipient makes Abs to Ags on transfused (donor cells) 11. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Sites and Factors that Affect Hemolysis Intravascular or extravascular hemolysis Depends on: Class of Ab Ability to fully activate complement cascade continued on next slide 12. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Sites and Factors that Affect Hemolysis Intravascular or extravascular hemolysis Extravascular hemolysis Most common RBC sensitized with Ab or complement Sensitized cells phagocytized by macrophages in spleen or liver continued on next slide 13. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Sites and Factors that Affect Hemolysis Intravascular or extravascular hemolysis Intravascular hemolysis Complement cascade activated C9 (MAC) RBC lysis 14. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Figure 19-1 Immune-mediated extravascular hemolysis. Erythrocytes sensitized with antibody or complement (C3b) attach to macrophages via specific cell receptors for these immune proteins. 15. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-3 Factors Affecting the Rate of Hemolysis in Immune Hemolytic Anemias 16. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Mechanisms of Hemolysis Based on whether IgM, IgG, and/or complement are present on RBC Three types: IgG-mediated Complement-mediated IgM-mediated 17. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams IgG-Mediated Hemolysis IgG attaches to RBC membrane Ags via Fab region. Fc receptors FcR-I, -II, -III on macrophages of spleen Bind to Fc portion of Ab attached to RBC Macrophage pits the Ag/Ab complex continued on next slide 18. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams IgG-Mediated Hemolysis Fc receptors Damages RBC membrane RBC membrane reseals itself Repeated splenic passagecontinues to lose membrane, forms spherocyte Phagocytized by splenic macrophages 19. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams IgG-Mediated Hemolysis Ab-sensitized RBCs can be entirely engulfed by: Macrophages PMN (FcR-I, -III) NK cells (FcR-III)results in ADCC (Ab dependent cell-mediated cytotoxicity) 20. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams IgG-Mediated Hemolysis Spleen Lightly opsonized cells more efficiently removed Liver Removes heavily sensitized cells Splenomegaly is common 21. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Complement-Mediated Hemolysis Role of complement Sensitization Only portion of complement cascade activated and deposited on RBC membrane Lysis of RBCs Entire complement system activated and deposited on RBC membrane 22. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Complement-Mediated Hemolysis Initiation of complement activation Classic, alternate, lectin mechanisms Classic pathway Initiated by Ag/Ab reaction IgM Activates complement more efficiently Only requires one IgM molecule IgG (IgG1 and IgG3; occasional IgG2) Activation requires two IgG molecules 23. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Complement-Mediated Hemolysis Cascade initiated C1 binds to the Fc region of IgG or IgM. Activates C4, C2, C3 Activates the terminal components C5 to C9 Membrane attack complex (MAC) Lytic attack to RBC membrane Intravascular hemolysis when complement activation C1C9 is complete continued on next slide 24. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Complement-Mediated Hemolysis Cascade initiated Activations through C3 RBC sensitized with C3b Totally or partially engulfed by macrophages with receptors for C3b C3b on RBC cleaved by plasma C3b inactivator C3c dissociates from membrane. C3d no receptors on macrophages Normal RBC survival 25. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Figure 19-2 The complement cascade. The central event in complement activation is the activation of C3 by C3 convertases. This can occur by two separate but interrelated mechanisms, the classic and alternate pathways. The classic complement pathway is initiated by an antigenantibody reaction. The antigenantibody complex activates the C1q, r, s complex, which in turn activates C4 by proteolytic cleavage to C4a and C4b. C2 binds to C4b and is proteolytically cleaved by C1s to form C2a and C2b. The C4b2a complex serves as C3 convertase. In the alternate pathway, C3b serves as the cofactor of the C3-cleaving enzyme complex (C3b, P, Bb), also known as C3 convertase. Thus, C3b serves to prime its own activation. The C3b formed through the classic pathway can directly initiate the assembly of the alternate pathway C3 convertase. C3 can also be activated by spontaneous hydrolysis. The C3b complexes formed by the classic and alternate pathways activate C5 to C5a and C5b. Membrane damage is initiated by the assembly of C5b with C6, 7, 8, 9. 26. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams IgM-Mediated Hemolysis Macrophages do not have receptors for Fc portion of IgM. IgM is efficient activator of complement Intravascular Complement activation through C9 and RBC hemolyzes continued on next slide 27. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams IgM-Mediated Hemolysis Macrophages do not have receptors for Fc portion of IgM. IgM is efficient activator of complement. Extravascular Activation incomplete C3b coats RBCs and sensitized cells destroyed extravascularly via CR1 and CR3 receptors on macrophages. IgM can agglutinate cells in addition to activating complement. 28. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Laboratory ID of Sensitized RBCs Two agglutination techniques Salinedetects IgM antibodies AHG testdetects IgG and/or complement Direct AHG (DAT) Detects RBCs coated in vivo Required to differentiate AIHA from other types of HA continued on next slide 29. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Laboratory ID of Sensitized RBCs Two agglutination techniques AHG testdetects IgG and/or complement Indirect AHG (IAT) Detects antigens in plasma or serum (in vitro) Indicates alloimmunization or free autoAbs in patient's serum 30. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Figure 19-3 The zeta potential of erythrocytes keeps the cells about 25 nm apart when suspended in saline. IgG antibodies have a span of about 14 nm, not enough to bridge the gap between cells and cause agglutination. IgM antibodies, however, are pentamers with a span of about 35 nm, a distance sufficient to bridge the space between cells and cause agglutination. 31. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Laboratory ID of Sensitized RBCs Negative DAT in AIHA Can result from Insufficient number IgG molecules on RBCs Autoantibodies of IgA or IgM class Autoantibodies with low affinity for RBCs continued on next slide 32. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Laboratory ID of Sensitized RBCs Negative DAT in AIHA Newer techniques more sensitive Enzyme linked DAT Gel tests Flow cytometry Polybrene tests 33. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Laboratory ID of Sensitized RBCs Positive DAT in normal individual Healthy blood donors and hospitalized patients Positive DATNo shortened RBC survival continued on next slide 34. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Laboratory ID of Sensitized RBCs Positive DAT in normal individual Possible causes: Inefficient macrophage removal of sensitized RBCs Insufficient quantity of Ab on cell surface Subclass of Ab not recognized by macrophage continued on next slide 35. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Laboratory ID of Sensitized RBCs Positive DAT in normal individual Possible causes: Thermal amplitude of antibody (< 37C) + DAT due to presence of complement on RBCs Patients with hypergammaglobulinemia or receiving high-dose IV gamma globulin exhibit nonspecific binding. 36. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Autoimmune Hemolytic Anemias (AIHA) 37. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams AIHA Immune tolerance normally prevents formation of autoantibodies Autoimmune diseases occur because: Genetic predisposition Exposure to infectious agents (molecular mimicry) Defects in regulation of immune tolerance continued on next slide 38. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams AIHA Immune tolerance normally prevents formation of autoantibodies Subcategories Warm vs cold autoantibodies Further categorized as Primary vs secondary AIHA 39. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Accounts for ~ 70% of cases AIHA Optimal reactivity at 37C Usually IgG (rarely IgM, IgA) Most Abs react with "Rh protein" complex Do not react with Rh null or Rh deleted cells Occasionally have single specificity within Rh system (e.g., anti-e) continued on next slide 40. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Accounts for ~ 70% of cases AIHA Most hemolysis is extravascular via splenic macrophages. 41. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Idiopathic WAIHA Accounts for about 60% of cases of warm AIHA Acute idiopathic WAIHA Severe anemia Developing over two to three days Hemolysis is self limited Several weeks several years duration continued on next slide 42. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Idiopathic WAIHA Chronic idiopathic WAIHS Hemolysis is unabating. 43. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Secondary WAIHA associated with: Lymphoproliferative disease CLL, HD Neoplastic diseases Autoimmune disorders SLE, RA, Crohn's disease, and so on Certain viral and bacterial infections Vaccines 44. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Clinical findings Can occur at any age Incidence after age 40 Common presentation Symptoms of anemia continued on next slide 45. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Clinical findings Secondary AIHA Signs and symptoms of underlying disorder Mild to moderate splenomegaly > 50% patients, hepatomegaly in patients 46. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Laboratory findings Immune-mediated hemolysis + DAT Autoantibody in the serum Presence of spherocytes continued on next slide 47. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Laboratory findings Peripheral blood Moderate to severe normocytic/normochromic anemia Reticulocytosis Polychromasia, NRBCs, spherocytes, schistocytes 48. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Figure 19-4 BA blood smear from a patient with warm autoimmune hemolytic anemia (WAIHA). The marked anisocytosis is due to the presence of spherocytes and large polychromatophilic erythrocytes. The nucleated cells are erythroblasts (Wright stain, 1000 original magnification). 49. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Laboratory findings Bone marrow Erythroid hyperplasia, erythrophagocytosis Other lab tests + DAT + polyspecific AHG and anti-IgG monospecific AHG 30% + anti-C3 continued on next slide 50. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Laboratory findings Differential diagnosis from HS + DAT Autohemolysis test not corrected by glucose Non-homogeneous population of spherocytes 51. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-4 Laboratory Findings Associated with WAIHA 52. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Therapy Self-limited hemolytic disorders Do not require transfusions. Patients needing transfusions Difficulty finding compatible donor cells continued on next slide 53. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Warm AIHA Therapy Other therapies Immunosuppressive drugs, cytotoxic drugs Splenectomy Rituximab IVIGhigh dose intravenous immunoglobulin Plasma exchange and plasmapheresis 54. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Cold AIHA Accounts for ~ 1630% of cases of AIHA Optimal reactivity < 37C Usually IgM, with complement activation Rarely IgA or IgG Most Abs react with I/i Ags or Pr Ags continued on next slide 55. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Cold AIHA Accounts for ~ 1630% of cases of AIHA Severity of disease Related to thermal range of the Ab Most hemolysis due to complement- mediated lysis 56. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Cold AIHA Idiopathic or secondary Idiopathic CAS (cold agglutinin syndrome) Usually chronic, occurring after age 50 Ab involved is usually Monoclonal IgM/kappa with autoanti-I specificity continued on next slide 57. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Cold AIHA Idiopathic or secondary Secondary CAS Associated with infectious disease Usually acute, self-limiting Polyclonal autoAbs with specificity for Ii antigens anti-IM. pneumoniae anti-IInfectious mononucleosis anti-Prvaricella, rubella continued on next slide 58. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Cold AIHA Idiopathic or secondary Secondary CAS Associated with lymphoproliferative disorders Usually chronic, found in older individuals Monoclonal IgM Ab 59. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-5 Autoimmune Hemolytic Anemia Caused by Cold-Reacting Antibodies 60. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Cold AIHA Clinical findings Chronic or episodic hemolytic anemia RBC agglutination Areas of the body that cool to the Ab thermal range Sludging of blood flow within capillaries continued on next slide 61. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Cold AIHA Clinical findings Vascular changes Acrocyanosis Raynaud's phenomenon Pain with color change patterns in skin Hemoglobinuria and splenomegaly 62. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Cold AIHA Laboratory findings Automated blood counts Falsely RBC Falsely MCV Must warm blood and diluting reagents continued on next slide 63. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Cold AIHA Laboratory findings Mild to moderate anemia Normocytic/normochromic Polychromasia, spherocytes, clumps of RBCs, NRBCs, erythrophagocytosis Bone marrow Normoblastic hyperplasia 64. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-6 Criteria for Clinical Diagnosis of Cold Agglutinin Syndrome (CAS) 65. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Figure 19-5 Cold autoimmune hemolytic anemia from a patient with chronic lymphocytic leukemia. Some of the erythrocytes are in small clumps. Spherocytes are also present (peripheral blood, Wright stain, 1000 original magnification). 66. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Cold AIHA Laboratory findings Differential diagnosis Benign cold autoagglutinins vs pathologic cold agglutinins Pathologic cold agglutinins + DAT for polyspecific AHG and monospecific anticomplement antiserum Cold agglutinin testagglutinates RBCs at 020C in saline, reversible at 37C Titer usually > 1:1000 (normal 1:64) 67. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-7 Comparison of Characteristics of Pathologic Cold Agglutinins Found in CAS with Those of Benign Cold Agglutinins Found in Normal Individuals 68. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Cold AIHA Therapy Keeping extremities warm is most effective Secondary to lymphoproliferative disorder Chemotherapy Plasma exchange for acute hemolytic episodes Effective for short time 69. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Paroxysmal Cold Hemoglobinuria (PCH) Rare autoimmune hemolytic disorder Can occur at any age Massive intermittent acute hemolysis and hemoglobinuria Accounts for 3040% of all AIHA in children Most frequent < age 5 Associated with viral and bacterial infections continued on next slide 70. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Paroxysmal Cold Hemoglobinuria (PCH) Rare autoimmune hemolytic disorder Usually transient disorder Resolves spontaneously Transfusions may be needed in severe cases. 71. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Paroxysmal Cold Hemoglobinuria (PCH) Pathophysiology Bi-phasic complement fixing IgG antibody Donath Landsteiner antibody Binds RBCs at low temps (< 20C), activates complement continued on next slide 72. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Paroxysmal Cold Hemoglobinuria (PCH) Pathophysiology Bi-phasic complement fixing IgG antibody Upon warming to 37 Ab detaches RBC lysed by complement activation through C9 (MAC) Usual reactivityautoanti-P antibody 73. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Paroxysmal Cold Hemoglobinuria (PCH) Clinical findings Hemoglobinuria most common clinical symptom Jaundice, pallor, hepatosplenomegaly Raynaud's phenomenon can occur 74. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Paroxysmal Cold Hemoglobinuria (PCH) Laboratory findings Anemia depends on frequency and severity of attack. Hb drops sharplyCan as low as 5 g/dL. Hemoglobinemia, methemalbuminemia, hemoglobinuria continued on next slide 75. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Paroxysmal Cold Hemoglobinuria (PCH) Laboratory findings Neutropenia, neutrophil shift to left Reticulocytopenia, spherocytes serum bilirubin, BUN, LD serum complement, haptoglobin Erythrophagocytosis continued on next slide 76. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Paroxysmal Cold Hemoglobinuria (PCH) Laboratory findings DAT usually negative for antibodies DAT weakly + for complement IAT + if performed in cold Donath-Landsteiner antibodies Present in low titers < 1:32 Verified by D-L test 77. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-8 Donath-Landsteiner (D-L) Test for Detecting the Presence of D-L Antibodiesa 78. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Paroxysmal Cold Hemoglobinuria (PCH) Therapy PCH terminates with recovery from infection. Transfusion if hemolysis is severe Plasmapheresis if hemolysis persists Rituximab Avoid exposure to cold 79. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-9 Comparison of Cold Agglutinin Syndrome (CAS) and Paroxysmal Cold Hemoglobinuria (PCH) 80. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Mixed-Type AIHA Due to presence of warm-reacting IgG autoAb and cold-reacting IgM autoAb Both have high titer and thermal amplitude 50% of cases are idiopathic. Remainder associated with lymphoproliferative diseases, autoimmune diseases (e.g., SLE), or HIV continued on next slide 81. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Mixed-Type AIHA Due to presence of warm-reacting IgG autoAb and cold-reacting IgM autoAb Mixture of both intravascular (IgM) and extravascular (IgG) hemolysis Most patients respond to corticosteroids without transfusions. 82. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Drug-Induced Hemolytic Anemias 83. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Drug-Induced HA Acquired cause of hemolytic anemia Not all individuals taking the same drug develop HA. > 125 drugs identified Immune response to drug-induced alteration of RBC Must differentiate from: Drug-induced, nonimmune hemolysis Spontaneous autoimmune disorders 84. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Drug-Induced HA Uncommon acquired cause of HA Resolution is withdrawal of drug. Classic mechanisms Drug absorption, immune complex formation, autoantibody induction, membrane modification New "unifying" hypothesis continued on next slide 85. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Drug-Induced HA Uncommon acquired cause of HA New "unified" hypothesis Drug binds to RBC membrane. Abs produced to react with epitopes specific to drug Combination of drug and RBC proteins Epitopes primarily on RBC membrane Explains how patients develop more than one type of drug-induced Ab continued on next slide 86. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Drug-Induced HA Uncommon acquired cause of HA New "unified" hypothesis Two types: Drug dependentrequires presence of drug during testing Drug independentreacts without presence of drug Sensitized RBCs have shortened life span + DAT 87. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-10 Summary of Classic Mechanisms of Drug-Induced Immune Hemolytic Anemia 88. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Alloimmune Hemolytic Anemia 89. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Alloimmune HA Ab develops to a RBC Ag that the individual lacks. Individual exposed to transfused RBCs from another person Ags on transfused cells are lacking on RBCs of recipient. Stimulate production of Ab (alloAb) continued on next slide 90. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Alloimmune HA Ab develops to a RBC Ag that the individual lacks. Abs react only with cells that possess the Ag. Not the individual's own RBC continued on next slide 91. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Alloimmune HA Ab develops to a RBC Ag that the individual lacks. Detected by Ab screen (indirect AHg test) Seen in transfusion reactions and Hemolytic disease of the fetus or newborn (HDFN) 92. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Hemolytic Transfusion Reactions Result of: Interaction of foreign (nonself) Ags on transfused RBCs and patient's plasma Abs Immunologic destruction of donor cells continued on next slide 93. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Hemolytic Transfusion Reactions Result of: Two types of transfusion reactions Immediate (IgM) Occurring within 24 hr, intravascular hemolysis Delayed (IgG) Occurring 214 days after transfusion, extravascular hemolysis 94. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-11 Comparison of Acute and Delayed Hemolytic Transfusion Reactions 95. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Hemolytic Transfusion Reactions Therapy Acute Terminate transfusion Supportive care Delayed No treatment 96. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Hemolytic Disease of the Fetus and Newborn (HDFN) Feto-maternal blood group incompatibility Mother forms alloantibodies against fetal RBC antigens. IgG antibodies cross placenta and destroy fetal RBCs in utero. continued on next slide 97. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Hemolytic Disease of the Fetus and Newborn (HDFN) Feto-maternal blood group incompatibility Three categories: 1. Rh(D) caused by anti-D (more severe disease) 2. ABO caused by anti-A and/or anti-B (more common) 3. Other caused by Abs to other blood group system Ags 98. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Table 19-12 Comparison of Hemolytic Disease of the Fetus and Newborn Caused by ABO and Rh(D) 99. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Hemolytic Disease of the Fetus and Newborn (HDFN) Pathophysiology Four conditions must be met for HDFN to occur: Mother must be sensitized to RBC Ag that she lacks. Fetus must possess Ag to which mother has been sensitized. Mother must produce Abs to foreign Ags. Mother's Ab must cross placenta, enter fetal circulation. 100. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Hemolytic Disease of the Fetus and Newborn (HDFN) Laboratory testing Mother ABO and Rh typing, antibody screen (IAT) Baby ABO and Rh typing, DAT (elution if necessary to identify Ab) 101. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Hemolytic Disease of the Fetus and Newborn (HDFN) Laboratory findings Baby's peripheral blood: Macrocytic/normochromic, reticulocytes, leukocytosis with left shift, NRBCs Rh HDFN Marked polychromasia, mild or absent poikilocytosis, few (if any) spherocytes, bilirubin, + DAT continued on next slide 102. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Hemolytic Disease of the Fetus and Newborn (HDFN) Laboratory findings Baby's peripheral blood: ABO HDFN NRBCs, schistocytes, spherocytes, polychromasia, sl bilirubin, weakly + DAT 103. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Hemolytic Disease of the Fetus and Newborn (HDFN) Therapy Prevent hyperbilirubinemia and anemia Intrauterine transfusion Viability of fetus affected Phototherapy (after birth) to reduce bilirubin Exchange transfusion if bilirubin is rising > 1 mg/dL/hour or significant anemia 104. Clinical Laboratory Hematology, Third Edition Shirlyn B. McKenzie | J. Lynne Williams Hemolytic Disease of the Fetus and Newborn (HDFN) Rh immune globulin (RhIG) Passive injection that contains anti-D that prevents maternal immunization Given at 28 weeks gestation and following birth of Rh+ infant Dose determined on number of fetal cells in maternal circulation Kleihauer-Betke Test Rossette Test Flow cytometry