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CLS > WAIHA > Flashcards

WAIHA Flashcards

1
Q

What do most autoantibodies react with?

A

High incidence RBC antigens (Rh blood group)

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2
Q

What do autoantibodies do?

A

Agglutinate, sensitize, or lyse RBCs of random donors and self

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3
Q

What are some discrepancies caused by?

A

Autoantibodies coating RBCs

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4
Q

If DAT is positive, what does that mean?

A

There is a positive autocontrol, which means there’s an autoantibody

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5
Q

Individuals who make antibodies against antigens on their own red blood cells (autoantibodies) with resultant hemolysis suffer from ____

A

autoimmune hemolytic anemia (AIHA)

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6
Q

Is it AIHA if person has not been recently tranfused?

A

No

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7
Q

When your bone marrow is keeping up with the amount of RBCs being destroyed?

A

Compensated anemia

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8
Q

What is the retic count for compensated anemia?

A

High

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9
Q

What is the H/H for compensated anemia?

A

Mildly low

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10
Q

blood test that measures how fast red blood cells called reticulocytes are made by the bone marrow and released into the blood

A

Retic count

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11
Q

the proportion, by volume, of the blood that consists of red blood cells expressed in %

A

hematocrit

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12
Q

the oxygen-carrying protein pigment in the blood, specifically in the red blood cells expressed as g/dL

A

hemoglobin

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13
Q

When your bone marrow is not keeping up with the amount of cells being destroyed

A

Uncompensated anemia

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14
Q

What is seen in peripheral smear of someone with uncompensated anemia?

A

Macrocytosis and spherocytosis

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15
Q

What is the retic count for uncompensated anemia?

A

more than 3%

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16
Q

What is the level of unconjugated bilirubin and LDH in uncompensated anemia?

A

High

high LDH = damaged tissues

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17
Q

Bilirubin that is bound to a certain protein (albumin) in the blood

A

Unconjugated bilirubin

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18
Q

What is the haptoglobin levels in uncompensated anemia?

A

Low

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19
Q

How do you confirm if someone has AIHA?

A

DAT (and eluate if positive)

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20
Q

Can AIHA antibodies be warm or cold reactive?

A

Most are warm, some are cold

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21
Q

Can AIHA antibodies be drug induced?

A

Yes

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22
Q

What do cold reactive autoantibodies react best with?

A

Enzyme-treated cells (ficin at IS)

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23
Q

What class of Ig are cold reactive autoantibodies?

A

IgM

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24
Q

Can cold IgM autoagglutinins activate complement in vitro?

A

Yes, by binding to RBC surface (causing a positive DAT)

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25
Q

At what phase can reactivity be seen in cold reactive autoantibodies?

A

At Coombs (AHG) using polyspecific AHG

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26
Q

What AHG is used for D/weak D typing?

A

Monospecific IgG AHG

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27
Q

What can be done to remove cold autoantibodies coating RBCs?

A

Use monoclonal IgG reagents, wash cells at 37C, ADSORPTION

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28
Q

Do cold reactive autoantibodies interfere with detection and ID of RBC ALLOantibodies?

A

YES

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29
Q

Do benign cold autoantibodies interfere with using polyspecific AHG?

A

Yes

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30
Q

What happens when RBCs are heavily coated with cold autoantibodies?

A

False positive reactions with ABO reagents; spontaneous agglutinations (so need to wash at 37C)

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31
Q

Can you use pre-warmed testing for cold autoantibodies?

A

Not for recently transfused patients (within 3 months) or inaccurate transfusion history

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32
Q

What specificity do most cold autoantibodies have?

A

Cold anti-I specificity (NOT little i)

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33
Q

What specificity do some cold autoantibodies have?

A

Cold anti-H in group O and A2 people who have the most H antigen so they react best

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34
Q

Lacks H antigens; therefore anti-H is a potent alloantibody which reacts at cold temp with all cells except rare Oh cell and capable of causing rapid intravascular destruction

A

Bombay

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35
Q

Occurs in old people (around 50); antibody specificity is always anti-I, usually seasonal and not severe

A

Idiopathic Cold AIHA (Cold Hemagglutinin Disease)

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36
Q

What is the clinical criteria for diagnosis of Idiopathic Cold AIHA (Cold Hemagglutinin Disease)?

A

Acquired hemolytic anemia with a history of acrocyanosis, jaundice, Raynaurd’s and hemoglobinuria on exposure to cold

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37
Q

What serological tests are performed for Idiopathic Cold AIHA (Cold Hemagglutinin Disease)?

A

DAT; cold agglutination titer; reactivity in patient’s serum

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38
Q

What causes Paroxysmal Cold Hemoglobinuria (PCH)?

A

a biphasic IgG autoantibody that fixes complement at low temperature, causing intravascular hemolysis, but ultimately dissociates at a higher temperature

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39
Q

Who is PCH common seen in?

A

Children with viral illnesses, but incidence of 1-2%

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40
Q

How do you solve problems associated with cold agglutinins?

A

Get out of cold climate

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41
Q

What is severe and rapidly progressive anemia?

A

Intravascular anemia

42
Q

What percent of warm reactive autoantibodies (WAIHA) are true autoimmune hemolytic anemia (AIHA)?

A

70%

43
Q

Is WAIHA severe enough to require a transfusion?

A

Yes

44
Q

What is the hemoglobin for people with WAIHA?

A

low levels less than 7 g/dL

45
Q

What causes Warm Autoimmune Hemolytic Anemia (WAIHA)?

A

Gradual onset that can be accelerated by trauma, surgery, pregnancy, or psychological stress

46
Q

What are the symptoms of WAIHA?

A

pallor, weakness, dizziness, labored breathing (dyspnea), jaundice, unexplained fever

47
Q

Is hemolysis in WAIHA acute at onset?

A

Yes, it may stabilize or accelerate at variable rate

48
Q

What is seen in a peripheral blood smear of someone with WAIHA?

A

Polychromasia, spherocytosis, nRBCs

49
Q

If your retic count goes down, what does that mean?

A

Your bone marrow cannot compensate for the amount of RBCs destroyed?

50
Q

What causes the RBC hemolysis in WAIHA?

A

IgG, with IgG subclasses 1 and 3 (with IgG3 being the most destructive)

51
Q

At what phase does IgG react best at in WAIHA?

A

At Coombs (AHG)

52
Q

Do IgG of WAIHA agglutinate after 37C incubation?

A

No, only after AHG

53
Q

Do IgG of WAIHA activate complement?

A

Yes

54
Q

Are IgG of WAIHA enhanced by enzyme?

A

Yes

55
Q

Do IgG of WAIHA react with high-incidence RBC antigen and have a general specificity with Rh group?

A

Yes, so Rh typing can be a problem

56
Q

Is ABO group affected by WAIHA?

A

No

57
Q

the primary means for deter- mining whether immune-mediated destruction of red blood cells is contributing to a patient’s anemia

A

DAT

58
Q

What class always fixes complement?

A

IgM

59
Q

What does a positive DAT mean?

A

Confirms the presence of IgG or complement on RBCs in vivo

60
Q

What is associated with binding of IgG or IgM on RBCs?

A

Immune-mediated hemolytic anemia

61
Q

What does a positive DAT mean for an anemic patient who has not been recently transfused?

A

Autoimmune hemolytic anemia (AIHA)

62
Q

What is an alloadsorption?

A

Using donor/reagent RBCs with known antigen phenotypes to adsorb patient’s autoantibodies; adsorbing cells should not have the antigens against which the alloantibodies react

63
Q

What is an autoadsorption?

A

Using patient’s own RBCs to remove autoantibodies, and alloantibodies should not bind since patient should lack the corresponding antigen

64
Q

What is the procedure to detect and identify alloantibodies for people NOT recently transfused?

A

Warm autoadsorption: patient serum and cells are incubated at 37C, then use patient’s own cells to remove autoantibodies… leaving alloantibodies in the serum

65
Q

What is the procedure to detect and identify alloantibodies for people that were recently transfused?

A

Alloadsorption

66
Q

What is the cell selection for alloadsorption based on?

A

Based only on clinically significant antigens: D, C, E, c, e, K, Fya, Jka, Jkb, S, and s

67
Q

What is the cell selection for alloadsorption based on?

A

Based only on clinically significant antigens: D, C, E, c, e, K, Fya, Jka, Jkb, S, and s

68
Q

If there’s no alloantibodies detected, what units can be transfused?

A

Random units of appropriate ABORh type can be used

69
Q

Mediated by autoantibodies that react at 37C

A

WAIHA

70
Q

What antibodies are associated with WAIHA?

A

IgG

71
Q

What is the typical results of WAIHA?

A

Positive autocontrol, positive DAT, and positive antibody screen with all reacting at IAT

72
Q

If there’s clinically significant alloantibodies present, what units are tranfused?

A

Units should lack the corresponding antigen (because you don’t want the alloantibodies to react with the corresponding antigens)

73
Q

If the autoantibody has a clear specificity and patient has active hemolysis, what unit is transfused?

A

Units lacking the antigen

74
Q

If the autoantibody has a broad specificity, what unit is tranfused?

A

Units are compatible with any alloantibodies detected

75
Q

What WAIHA treatment is used for patients who have a positive initial response to steroids?

A

Splenectomy

76
Q

What WAIHA treatment raises hematocrit levels and lowers retic count (=less RBC destruction) that’s not transfusion?

A

Prednisone therapy

77
Q

What WAIHA treatment decreases antibody production and removes a potent site of RBC destruction?

A

Splenectomy

78
Q

What WAIHA treatment interferes with antibody synthesis?

A

Immunosuppressive drugs

79
Q

What is the site of hemolysis for WAIHA?

A

Extravascular (no cell lysis)

80
Q

What are the four classic mechanisms that have been proposed to cause drug-induced problems?

A
  • Immune complexes
  • Drug adsorption
  • Membrane modification
  • Autoantibody formation
81
Q

When should DIIHA be suspected?

A

When there’s hemolysis or a positive DAT for no other reason AND if there’s a drug history

82
Q

What causes DIHA (Drug-Induced Sensitization and Immune Hemolytic Anemia)?

A

Drugs or Immune complex mechanism

83
Q

What happens during a DIIHA?

A

drugs combine with plasma proteins to form immunogens (IgG or IgM recognizes determinants on drug)

84
Q

What happens when patient takes drugs after immunization?

A

Drug-antidrug complex may occur, leading to activation of complement cascade, leading to lysis

85
Q

What hemolysis do patients with DIIHA present?

A

Acute intravascular hemolysis

86
Q

What action should be taken for patients with DIIHA?

A

Withdraw the drug

87
Q

What is the DAT and screen result in patients with DIIHA?

A

Positive DAT and negative screen

88
Q

What happens during a drug adsorption mechanism?

A

Drugs bind firmly to proteins including proteins on the RBC membrane

89
Q

What drug causes a positive DAT and may cause hemolytic anemia?

A

Cephalosporins

90
Q

What happens during a membrane modification (non-immunologic protein adsorption)?

A

Uptake of immunoglobulins or complement components is not the result of Ag/Ab-reactions

91
Q

Is there a treatment for membrane modification (non-immunologic protein adsorption)?

A

No

92
Q

What does non-immunologic mean?

A

Antibodies with blood group specificities are not involved (so tests with patient’s serum and eluate are negative)

93
Q

What serological reactions are observed with drug-induced positive DATs?

A
  • Immune complex
  • Drug adsorption
  • Drug-independent
  • Membrane modification
  • Methyldopa-induced
94
Q

What induces the production of an autoantibody that recognizes the RBC antigens?

A

Aldomet

95
Q

What is serologically indistinguishable from antibodies seen in WAIHA?

A

Autoantibodies produced because of aldomet (membrane modification)

96
Q

Which mechanism is the only one that has positive eluates?

A

Methyldopa-induced

97
Q

Are any cells tests for Membrane modifcations?

A

No, it’s non-immunologic protein adsorption

98
Q

What is the frequency of hemolysis for immune complex?

A

small doses of drugs may cause intravascular hemolysis

99
Q

What is the frequency of hemolysis for drug adsorption?

A

3-4% get extravascular hemolysis

100
Q

What is the frequency of hemolysis for membrane modifcation?

A

None; 3% develop positive DAT

101
Q

What is the frequency of hemolysis for methyldopa-induced?

A

less than 1% develop hemolytic anemia that mimics WAIHA; 15% develop positive DAT

CLS (6 decks)

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