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Immunohematology > Exam 5? > Flashcards

Exam 5? Flashcards

1
Q

What are the reagents in DAT to detect antibodies on RBCS IN-VIVO?

A

Polyspecific is used first then Monospecific Anti-IgG, and Monospecific Anti-C3d

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2
Q

In DAT, strength of agglutination is proportional to…?

A

Amount of bound protein

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3
Q

What must happen in DAT before antiglobulin reagents are added?

A

RBCs must be washed 3 - 4 times with a dry button at the end.

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4
Q

What are the three reasons to perform a DAT?

A
  1. Screen for clinically unexpected autoimmune phenomena
  2. Detect early manifestation of immune response to recent transfusion
  3. Assist in diagnosis of HDFN
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5
Q

What is the anticoagulant of choice for DAT?

A

EDTA

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6
Q

What should you do to a patient’s EDTA blood specimen if there is cold hemagglutinin suspected?

A

Keep the sample at 37C

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7
Q

A positive DAT does not mean what for the RBCs?

A

Shortened survival

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8
Q

True or false, there cannot be a clinical problem for patients with a positive DAT?

A

There can be. It can occur in 1:1,000 - 1:-14,000 blood donors and 1% - 15% of hospital patients

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9
Q

What is limit of detection for DAT? Give IgG and C3d

A

IgG is 100 - 500 molecules of IgG per RBC. For C3d it is 400 - 1100 molecules of C3d per RBC.

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10
Q

Healthy individual’s range for IgG molecule per RBCs?

A

5 - 90 molecules of IgG per RBC

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11
Q

Healthy individual’s range for C3d molecule per RBCs?

A

5 - 40 molecules of C3d per RBC

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12
Q

What are some causes of a positive DAT?

A
  1. Autoantibodies
  2. Alloantibodies - HTR
  3. Passively acquired alloantibodies (plasma derivatives)
  4. Maternal alloantibodies
  5. Nonspecifically adsorbed proteins or membrane modification
  6. Drug induced antibodies
  7. Antibodies produced by passenger lymphocytes
  8. Complement activation due to bacterial infection, atuoantibodes or alloantibodies
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13
Q

True or false, An autocontrol run as part of antibody work up is the same as DAT.

A

False. An autocontrol run as part of antibody work up and is not the same as DAT. Autocontrol goes through different steps than DAT. In DAT cells are taken directly to AHG, no adding of serum or enhancement, no incubation, detects IN-VIVO sensitization.

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14
Q

What are reasons for a false positive DAT?

A
  1. Want to detect IN-VIVO sensitization not in vitro
  2. False positive most often associated with using refrigerated or clotted samples
  3. Any positive obtained on clotted sample should be confirmed with an EDTA sample.
  4. EDTA will provide RBCs for elution if necessary
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15
Q

What is crucial to investigating a patient that may have an autoantibody?

A

Patient history! Look for…
1. History of recent transfusion
2. Prescribed drug associated with immune hemolysis
3. History of hematopoietic progenitor cell or organ transplant
4. Administration of IVIG or IV anti-D

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16
Q

How should a serologic investigation proceed?

A

First, DAT with monospecific anti-IgG and anti - C3d to characterize proteins coating RBCs (maybe polyspecific before monospecific?). Second test serum/plasma to detect and ID clinically significant antibodies to red cell antigens. You may have to distinguish auto- from allo-antibodies if present. The last thing is to do an elution from DAT positive RBCs to define whether coating protein has red cell antibody specificity.

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17
Q

If an elution’s control is positive is the elution results valid?

A

No it is not. If it is positive then that means there wasn’t enough washing done. It should be negative indicating the RBCs have been properly washed.

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18
Q

What is the principle of doing a elution?

A

Elution technique dissociate antibodies from sensitized red cells so that the antibodies can be identified.

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19
Q

What are situations that would lead to no further testing for an autoimmune hemolytic anemia?

A
  1. No unexpected antibodies present in serum/plasma
  2. Only autoantibody detected in eluate
  3. No recent transfusion
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20
Q

What are reasons for further studies on a specimen?

A
  1. Confirm specificity of alloantibody if present
  2. If DAT positive but serum/plasma and elution studies are negative suspect drug induced hemolysis- send to reference lab.
  3. If ABO incompatible components transfused test for anti-A and anti-B
  4. If patient is an infant perform appropriate testing on maternal sample and elution on cord cells.
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21
Q

What are the steps of autoadsorption?

A
  1. Remove serum; treat patient’s RBCs to remove existing auto antibodies.
  2. Wash RBCs 3 - 4 times after incubation
  3. Return patient’s serum to RBCs and incubate for 30 - 60 minutes.
  4. Centrifuge then transfer serum to 2nd tube of treated cells
  5. Incubate 30 - 60 minutes and centrifuge
  6. Remove serum and test for alloantibody
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22
Q

What are the steps for differential allogeneic adsorption?

A
  1. Separate tubes, incubate patient’s serum with three different phenotyped RBC samples for 30 - 60 minutes
  2. Remove serum and test each separately with panel cells to determine specificity.
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23
Q

What are the two types of cold autoadsorptions?

A

Rabbit erythrocyte stroma test (rest)
and cold auto adsorptions.

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24
Q

What are the two types of warm autoadsorptions?

A

W.A.R.M. and Warm Auto adsorption

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25
Q

Which cold autoadsorption test can be performed on a patient that has been recently transfused?

A

REST, Rabbit Erythrocyte Stroma Test not cold autoadsorption test.

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26
Q

Which cold autoadsorption test can be performed on a patient that has not been recently transfused?

A

Cold autoadsorption test

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27
Q

What should the MLS be cautious about when doing a REST, Rabbit Erythrocyte Stroma Test?

A

The test may adsorb out clinically significant antibodies to D, E, Vel antigens, and IgM antibodies regardless of specificity.

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28
Q

What coagulant is used for a cold autoadsorption test?

A

EDTA and it should be kept warm

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29
Q

A negative cold autoadsorption test means…?

A

Negative - no alloantibody, run panel

30
Q

A positive cold autoadsorption test means…?

A

Alloantibody present run panel

31
Q

In the cold autoadsorption test if all cells are positive results mean…?

A

Repeat with 1X adsorbed sample

32
Q

What is a limitation for cold autoabsorption test?

A

Will not remove a high titer cold agglutinin completely

33
Q

The supernatant in Cold autoabsorption is used for?

A

Ab screen, reverse grouping cells, and autocontrol.

34
Q

Define immune hemolytic anemia

A

Shortened RBC survival mediated through immune response specifically by humoral antibody

35
Q

What are the three categories of immune hemolytic anemia?

A
  1. Autoiummue (AIHA)
  2. Alloimmune
  3. Drug induced (DIIHA)
36
Q

Give examples of AIHA

A
  1. Warm autoimmune hemolytic anemia (WAIHA)
  2. Cold agglutinin syndrome (CAS)
  3. Mixed type - Both warm & cold autoantibodies present
  4. Paroxysmal cold hemoglobinuria (PCH)
37
Q

Give examples of alloimmune

A
  1. Hemolytic transfusion reaction (HTR)
  2. HDFN
38
Q

Give examples of Drug induced (DIIHA)

A
  1. Drug dependent
  2. Drug Independent
39
Q

List characteristics of immune red cell destruction.

A
  1. Possibly decrease H&H
  2. Elevated reticulocytes
  3. Elevated LDH
  4. Decreased Haptoglobin
  5. Elevated Unconjugated bilirubin
  6. Hemoglobinemia and/or hemoglobinuria may indicate acute hemolysis or intravascular RBC destruction.
40
Q

What are the terms to describe antibodies directed against an individual’s own RBCs?

A

Autoantibodies or autoagglutinins

41
Q

If a patient’s RBCs are coated with autoantibody, the patient may present with…?

A
  1. ABO discrepancy
  2. Positive Rh control
  3. Positive DAT
42
Q

Studies in animal models suggest what about autoantibodies?

A

They occur because of a failure of the immune regulatory response. The immune system should be removing antibodies that response to the self antigen.

43
Q

What are the two body’s response to immune RBC destruction?

A

Compensate or uncompensate anemia.

44
Q

Describe RBC destruction and synthesis in uncompensated anemia.

A

The rate of RBC production will be almost equal to the rate of RBC destruction

45
Q

Describe uncompensated anemia

A

Rate of RBC destruction exceeds rate of RBC production.

46
Q

What are the three classification of AIHA?

A

Cold reactive, warm reactive, or drug induced

47
Q

How are autoantibodies characterized?

A

By their optimal temperature of reactivity.

48
Q

List the temperatures (excluding drug induced) of warm reactive and cold reactive.

A

Warm - 30 to 37C which are about 70% of cases
Cold reactive is 4C to 30C which are about 18%
Drug induced are about 12% of cases.

49
Q

What are the immunoglobulins involved in warm and cold autoantibodies?

A

Warm is IgG and Cd3. Cold is C3 only

50
Q

What are the antibodies involved in warm autoantibodies and cold autoantibodies?

A

Warm - Broad specificity
Cold - Anti Big I

51
Q

What are the differences between warm and cold autoantibodies for severity?

A

Warm - Insidious to acute anemia severe.
Cold - Chronic Anemia (9-12 g/dL)

52
Q

What are the symptoms of cold and warm autoantibodies?

A

Warm - Fever, jaundice, splenomegaly, hepatomegaly, and adenopathy.
Cold - Hemoglobinuria, acrocyanosis, Raynaud’s w/ cold exposure but no organomegaly.

53
Q

What are transfusions like between warm and cold autoantibodies?

A

Warm - Great caution
Cold - Tolerated blood warms

54
Q

When are cold reactive autoantibodies frequently encountered?

A

Serologic testing

55
Q

Typically cold agglutinins have a relatively _____ titer.

A

Low titer <64 @ 4C

56
Q

Cold agglutinins can interfere with

A
  1. ABO/Rh typing
  2. DAT
  3. Antibody detection & ID
  4. Compatibility testing
57
Q

Anti- little i reacts to…

A

Anti - Big I

58
Q

Cold agglutinins are found in…

A

Group A1 and A1B (and occasionally group B) may have anti-H specificity

59
Q

Acute conditions of pathologic cold agglutinins are

A

Mycoplasma pnemouniae - Anti - Big I
Infectious mononucleosis - Anti - Little i
Lymphoproliferative disorder - Anti - Little i

60
Q

The antibody usually behind cold hemagglutinin is

A

IgM

61
Q

How are cold hemagglutinin disease specimen characterized in an EDTA sample?

A

If they aren’t kept warm (as recommended) they will appear clotted in an EDTA tube.

62
Q

A peripheral smear of a patient with cold hemagglutinin disease would show?

A

Agglutinated RBCs, polychromasia, mild to moderate anisocytosis and poikilocytosis.

63
Q

In a patient with cold agglutinin disease why is complement only detected/present?

A

IgM binds in-vivo where temperature falls to 32C or less. When the IgM and bound RBCs return to warmer circulation IgM dissociates leaving RBCs coated with complement only.

64
Q

Would an elution be negative or positive for a patient with cold agglutinin disease?

A

Negative, because no antibodies are bound only complement.

65
Q

What is the treatment for patients with cold hemagglutinin disease?

A

Keep warm and avoid the cold. If they are rich move to a milder climate.

66
Q

What are transfusions like for a patient with cold agglutinin disease?

A

Rarely done however the blood is kept warm while being transfused. The blood is prewarmed for compatibility testing or use cold autoadsorbed serum.

67
Q

PCH, Paraoxysmal cold hemoglobinuria

A

Different from PNH in which hemolysis is caused by acid produced during sleep. Its caused by a biphasic hemolysin which induces hemolysis after exposure to cold. The Donath-Landsteiner antibody is produced with an Anti-P specificity.

68
Q

How does PCH present?

A

Hemoglobinuria and hemoglobinemia

69
Q

Describe biphasic hemolysin (autoantibody).

A

Binds to RBCs at low temperature. Binds complement. Dissociates when temps are warmer.

70
Q

Describe the Donath-Landsteiner Test

A

Goal is to see if RBCs lyse during the temperature change. RBCs are chilled to low temperature and then warmed to 37C. The test is positive if RBCs hemolyze (serum goes red).

71
Q

In warm autoantibody cases, what removes sensitized RBCs in the body?

A

Reticuloendothelial system (RES) cells of liver and spleen

72
Q

This test is best for getting IgG immunoglobulins to react.

A

IAT

Immunohematology (9 decks)

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