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TXN243 > Autoimmune Hemolytic Anemia > Flashcards

Autoimmune Hemolytic Anemia Flashcards

1
Q

-defined as the shortened RBC survival mediated through the immune response.

A

Immune Hemolytic Anemia

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2
Q

-Process in which erythrocytes are destroyed prematurely by an immune mediated process.

A

Immune Hemolytic Anemia

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3
Q

-Hemolysis resulting from antibodies or complement, or both attaching to the red blood cell membrane.

A

Immune Hemolytic Anemia

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4
Q

are serum proteins that interact with each other to initiate complement dependent cell mediated lysis

A

Complement

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5
Q

Complement involvement can be confirmed with a positive direct anti globulin test

A

C3d

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6
Q

-occurs within the vascular system and results from the activation of the classical complement pathway

A

Intravascular Hemolysis

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7
Q

Ig_ is a very efficient activator of complement because of its PENTAMERIC structure. A single molecule of IgM is capable of initiating complement activation by the classical pathway.

A

IgM

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8
Q

__________ Hemolysis
-is the phagocytosis of red cells within the mononuclear phagocyte system (MPS)
-2 major organs involved are _______ and ________.

-Antibody coated red cells interact with the __receptors (line the splenic cord) resulting in complete or partial phagocytosis (if it cannot repair itself then partial spherocytes are formed).

-Spherocytes lack deformability and become physically trapped in the spleen, those that escape are seen in the peripheral smear.
-Cells sensitized by both IgG and C3b/C3d are removed in the liver and spleen.

A

Extravascular
liver and spleen

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9
Q

-deifned as Patient’s immune system fails to recognize own red cell antigens as “SELF”.
-Control mechanisms for autoreactive antibodies are lost and antibodies are directed against the patient’s own red cells.
-As a result, patients produce Autoantibodies that bind to there own red cells.
- Can be primary or secondary to another disease.

A

Autoimmune Hemolytic Anemia (AIHA)

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10
Q

MAJOR TYPES OF AIHA

  1. _______ AIHA
    -70% of Autoimmune Hemolytic Anemia
    -Most are IgG antibodies
    -Hemolysis is extravascular and occurs in the spleen
    -Often have some Rh specificity (Anti-e)
    -Can be idiopathic with no underlying disease process
    -Can be due to underlying condition or medication (secondary)
    -Range from mild to severe (significance varies)
A

Warm Autoimmune Hemolytic Anemia

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11
Q

Disorders Associated:
-Lymphoproliferative disorders such as CLL, Hodgkin’s disease, Non-Hodgkin’s Lymphoma
-Autoimmune disorders such as lupus, and Rheumatoid Arthritis
-Neoplastic Disorders such as solid tumours in the ovary, breast, and pancreas
-Viral Infections such a Hep A or B
-Chronic Inflammatory Disease

A

WAIHA

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12
Q

Identify which AIHA is this?

Lab Findings:
-Red cells are lysed and hemoglobin is released
-Hemoglobinuria

CBC results:
-Normal MCV
-Rule of 3 acceptable
-Very increased MCHC
-PBS: spherocytes and increased polychromasia

A

Warm AIHA

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13
Q

Identify which AIHA is this?

  • Decreased RBC
  • Increased MCV
  • Rule of 3 violation
  • Very increased MCH
  • Very increased MCHC
  • PBS: agglutination present
A

Cold AIHA

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14
Q

Serological problems of WAIHA

-* The autoantibody present in the serum may mask an underlying alloantibody, since it reacts with all red cells (donor and panels).

  • Usually directed against an antigen found on all human red cells
  • Panagglutination
  • Sometimes specific for a high incidence antigen (difficult to find units for patient).
  • The patient’s red cells are strongly coated with the autoantibody, which interferes with serological testing such as phenotyping.
A
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15
Q

Investigating and Detecting a WARM Autoantibody

  • Antibody Screen is ________ in MTS and IAT tube method
  • Possible ________ grouping anomaly
  • If you suspect a Warm: Set up a panel with an Auto Control, and DAT testing.
A

Positive
Reverse

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16
Q

Antiglobulin Test

-Principle of test
Antibodies are _______ globulins, an antibody to gamma globulin can form bridges between red cells sensitized with antibody and cause them to__________. Because some IgG and IgM antibodies can also cause ___ to attach to the red cells, Polyspecific AHG serum also contains Anti-C3.

Reagent:
IgG (Anti-IgG)
and/or
Complement (Anti-C3d, Anti-C3b)

The Antiglobulin test is important because it detects ___ Antibodies and _________ proteins that have attached to red cells either in vitro or in vivo.

A

gamma
agglutinate
C3

IgG
Complement

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17
Q

The Antiglobulin Test (Coombs)

DAT or IAT?

_____-Detects Antibody or Complement that has attached to the Red Cell membrane in VIVO

_____-Detects Antibody or Complement that has attached to the Red Cell membrane in VITRO

A

DAT

IAT

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18
Q

The Antiglobulin Test (Coombs)

DAT or IAT?

  • Detects IgG or complement bound to RBCs in vivo
  • In the Procedure, AHG reagent is added directly after the RBCs have been washed.
  • No incubation is required
  • Agglutination indicates that either IgG or Complement is attached to the RBCs.
A

DAT

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19
Q

The Antiglobulin Test (Coombs)

DAT or IAT?

  • Detects IgG or complement bound to RBCs in vitro
  • 2 step procedure
    Antibodies (in serum/plasma) is incubated at 37 ̊C with RBC
    Antigens in vitro.
  • RBC suspension is washed
  • Combined with AHG reagent to detect agglutination
A

IAT

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20
Q

The Antiglobulin Test (Coombs)

DAT or IAT?

Procedure is:
* Wash 5% cells, add Polyspecific AHG after washing, centrifuge and read macroscopically.
* Confirm all negative reactions under the microscope
Sit for 5 minutes, read macroscopically and under the microscope.
* Add Coombs Control to negative tubes only.

A

DAT testing

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21
Q

The Antiglobulin Test (Coombs)

DAT or IAT?

Procedure:
* Add patient plasma/serum to known cells, read at IS, 37 ̊C and AHG.
* Centrifuge and read macroscopically at IS.
* Incubation required
* Incubate at 37 ̊C and read macroscopically.
* Wash cells, Add Polyspecific reagent read macroscopically and under the microscope.
* Add Coombs control to negative tubes only.

A

IAT testing

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22
Q

-Required as a control system when AHG results are Negative (No agglutination).
-After addition of Coombs, Agglutination must be present to validate testing.
-Commercial Reagents are typed O Red Cells.

False negative results are caused by:
1) Failure to add the AHG reagent
2) Failure of the AHG reagent to react
3) Failure to wash the RBCs adequately

A

IgG sensitized cells

23
Q

Differential DAT

-* If the initial DAT using Polyspecific AHG is positive, then perform a Differential DAT.

  • Reagents used are
    1. ____________ anti-IgG
    2. _____________Anti-Complement (-C3b, -C3d, -C4b or- C4d).

C3d, C3b, C4b or C4d are the complement components that remain on the Red Blood cell if the complement cascade has been activated.

For Testing of Complement in a Differential DAT, must let negative reactions sit for___ mins RT to enhance the complement reactions.

A

Monospecific
Monospecific

5

24
Q
A
25
Q

POSITIVE DAT
AIHA vs. Transfusion Reaction

  • A positive DAT can be diagnostic of AIHA.
  • It is also a hallmark of a Transfusion Reaction (patient makes antibody against the transfused donor cells).
  • Transfusion History is essential in the investigation of a positive DAT because IF there is no recent transfusion, then most likely it would be due to AIHA.
A
26
Q

DAT Challenges with Weak D testing

  • The Weak D test is positive because of the autoantibody present
  • The autoantibody is already attached to the red cells
  • Anti-D is NOT attached to the cells
  • This is a false positive result
  • Rh Control result would be positive as well
A
27
Q

DAT Challenges with Phenotyping

OBG antigen phenotyping that require IAT method:
* Add Antisera and Cells to perform IAT test
* Cells already coated with the IgG
* False positive (cannot tell if patient has the antigen or not)
* If blood is required, give RBC that lack that antigen, if there is a previous history from a different hospital use the information, if possible, genotype patient at CBS.

A
28
Q

Inadequate Washing for DAT procedure

  • Red cell washing is important in AHG testing, if the red cells are inadequately washed, any unbound antibodies and complement present can potentially bind to the AHG reagent and inhibit its reaction with the antibody or C3d molecules attached to the red cells.
    -THIS IS CALLED __________ OF THE AHG REAGENT
  • To detect this error, add _______ control to a negative reaction and if there is agglutination (reaction) then adequate washing has occurred.
A

NEUTRALIZATION

COOMBS

29
Q

Expected Reactions of WAIHA

Warm AutoAntibody expected reactions:
* Antibody Screen is positive
* Full Panel is positive
* Auto Positive
* DAT Positive
* Differential DAT usually indicates IgG and/or Complement on cells
* Perform Eluate to determine if autoantibody is present
* Possibly perform Autoabsorption to determine if there is an underlying antibody present.

A
30
Q

Further Testing for Autoimmune Hemolytic Anemia
* The autoantibody can mask alloantibodies that the patient produced before the development of AIHA.
* Testing is done on both cells and serum/plasma (eluate/panels)
* If blood is required, in most cases the PC are “Least Incompatible”, the Physician is notified, and consent is required.
* Packed cells are super phenotyped, matched exactly to the patient to prevent any development to alloantibodies.

A
31
Q

Crossmatching patients with WAIHA

  • Full phenotyped matching units are required for patients, to prevent an immune response to develop any antibodies.
  • If alloantibody is produced it can be masked and not detected due to patient’s Panagglutination.
  • If blood products are required, ______ negative red cells matched to the patients are issued with appropriate comments in LIS systems upon authorization by the attending physician.
A

ANTIGEN

32
Q

Warm Autoantibody Investigation
Testing the patient red cells and patient’s plasma

-_________ is the process of removal of an antibody from the plasma (often used interchangeably with adsorption).

-_________ is the process of adding specific antigen so that the antibody can attach to it and be removed from the plasma.

-The antigen adsorbs the antibody.

-________ is the process to remove an antibody bound to the cells (auto antibodies or donor cells coated with patient antibody in a transfusion reaction).

-________ can only be done if patient has been transfused within the last 3 months (in a transfusion reaction).

A

ABSORPTION
ADSORPTION
ELUTION
ELUTION

33
Q

___________

  • Used to eluate antibodies coating red cells
  • Unabsorbed antibody in patients serum is washed or absorbed with selected cells
  • The antigen and antibody complex is then disassociated (eluded) by the addition of a low pH solution
  • The eluted solution is then used to perform an antibody investigation
  • Last Wash must be tested
    along with the eluate
A

ELUTION

34
Q

Elution Limitations

Activity of the eluate depends on:
1) The number of Antibodies bound to cells
2) Dissociation of Antibody during last wash
3) Use of Patient cells older than __ hours may yield weaker reactions (alters final pH)
4) Failure to adjust __ to proper range can result in hemolysis of red cells

A

72
pH

35
Q

Eluate Methods

  • __________ which includes Heating or freezing
  • ___________method which uses acid or organic solvents
A

Temperature
Chemical

36
Q

Testing the eluate
* The eluate is tested against a panel of cells
* Results can indicate a specific antibody (Anti-e)
* OR the antibody can be non-specific and reacts
with all cells

A
37
Q

Eluate Methods
LAST WASH IS IMPORTANT

  • Cells are washed __-___ times before the actual elution is performed.
  • Do not Decant the last saline supernatant, save it and label it as “Last Wash”.
  • Perform the elution technique on the packed cells (after the last wash).
  • Run the “Last Wash” in parallel with the eluate on the same panel.
A
38
Q

Eluate Results

-If the washing technique was successful, the ___ should be antibody-free.
-A positive ______ with a negative ______ indicates that the antibody present was taken off from the red cells and not the plasma.

-* If a _____ Auto is present, the Eluate will react with everything (all cells on the panel are positive, non specificity).
-Non-reactive Eluate can indicate patient possibly having a -_____induced Hemolytic anemia.
- Eluates are not useful if Anti-_____ is attached to red cells.

A

LW
Eluate; LW

Warm
Drug-induced

C3d

39
Q

Drug Induced Auto Immune Hemolytic Anemia represents approximately 12% of various cases.

A
40
Q

Drug _______

  • Methyldopa or aldomet (Antihypertensive drug)
    -antibodies are produced by a drug
A

Independent

41
Q

Drug _______
* Considered True Autoantibody because they react to RBC antigen

A

Independent

42
Q

Drug _________
- Not all patients are affected
* Mild-moderate-severe
* May persist up to 2 years after drug discontinued

A

Independent

43
Q

Drug _________

  • Difficult to diagnosis since it mimics WAIHA
  • Positive DAT
  • IgG attached to RBC
A

Independent

44
Q

Drug _______

  • Possible for DAT to be positive up to 2 years after the drug is discontinued.
  • Positive Antibody Screen, Panel and Auto.
  • Eluate reacts with ALL cells
  • Possible Hemolysis (extravascular)
A

Independent

45
Q

Drug ________

  • Non-Specific uptake of immunoglobulins (normal plasma proteins) by the red cell membrane.
A

Dependent

46
Q

Drug ________
* Drug modifies the RBC membrane; plasma proteins nonspecifically absorb onto the patient red cells.

A

Dependent

47
Q

Drug ________
* NOT an actual antigen antibody reaction

A

Dependent

48
Q

Drug ________
* Cephalothin (Cephalosporin)
* DAT is positive to C3d
* Antibody Screen is negative
* Eluate is negative

A

Dependent

49
Q

Drug ________
* Drug covalently binds to red cell membrane protein, remains firmly attached.

A

Dependent

50
Q

Drug ________
* Antibody formed against the drug/protein complex
* Reacts ONLY with the drug treated cells

A

Dependent

51
Q

Drug ________
* DAT is Positive with IgG not Anti-C3
* Antibody Screen is negative (not an antigen and antibody complex) and eluate is often negative.

A

Dependent

52
Q

Drug ________
Penicillin is the most common drug (Drug Dependent)
Specific Test:
1) Coat the red cells with penicillin in vitro.
2) Perform antibody screen, the Penicillin coated cells are to run in parallel with regular screening cells.
3) Only drug coated cells will react.

A

Dependent

53
Q

Drug _________ __________
*Drugs combine with plasma proteins and become immunogenic
* Drug and Anti-Drug complex are formed, and binds complement.
* Complement non-specifically binds to red cell
* DAT is positive for Complement (C3d) and occasionally IgG
* Antibody Screen is negative
* Eluate is often negative
* Most common drugs are Quinidine

A

Dependent Immune

TXN243 (4 decks)

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