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Immunohematology - 4444 > Deck B > Flashcards

Deck B Flashcards

1
Q

Enzymes are protiens that

A

that increase the rate of a chemical reaction

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2
Q

What are the most commonly used enzymes

A

ficin and papain.

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3
Q
  1. Less commonly used enzymes are
A

enzymes are bromelin, pronase, trypsin, and chemotrypsin.

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4
Q

Some red cell antigens are _________ by enzymes and others are ___________ by enzymes

A

Destroyed and enhanced

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5
Q
  1. Enzyme-treated red blood cells are typically used in two instances:
A

 If a weakly reactive antibody is present, enzyme-treated red blood cells may be tested in an effort to enhance the reactivity and possibly clarify the reaction pattern or confirm the presence of the antibody.
 Use of enzyme-treated red blood cells can often help differentiate antibodies.

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6
Q
  1. Enzyme treatment can be performed in two ways:
A
  • The one-step technique: Enzyme is added as an enhancement to the tube containing test plasma and red blood cells and carried through the IAT phase of testing.
  • The two-step technique: Requires treatment of the red blood cells with enzyme and washing prior to the addition of patient plasma. This method is often preferred because the enzymes in the one-step technique are added directly to the patient’s plasma and any antibodies present may be damaged.
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7
Q
  1. ________ red blood cells must be used in tandem with the ____________ red blood cells to identify all antibodies present in a test sample.
A

Untreated and enzyme-treated

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8
Q

Neutralization definition

A

The inactivation of an antibody by combining it with a soluble form of the corresponding antigen.

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9
Q

Neutralization can aid in

A
  1. Inactivation of the antibody can aid in identification of a suspected antibody that does not react with an ideal pattern.
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10
Q

Neutralization

Sources of

A
  1. Sources of neutralizing substances include saliva, hydatid cyst fluid, urine, plasma, breast milk, and amniotic fluid.
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11
Q

Elution

A

Frees antibody that is bound to a red blood cell.

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12
Q

Uses of an elution

A

 Identify one or more antibodies attached to the red blood cell membrane.
 Prepare antisera or to detect and identify weakly reactive antibodies.
 Prepare DAT-negative red blood cells for further testing.
 It can be combined with adsorption techniques to remove specific antibodies or antibodies.
 Adsorption and elution techniques can be used to detect a weakly reactive antigen, such as a weak ABO subgroup.

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13
Q
  1. Methods that are best at releasing cold-reactive antibodies or antibodies that have a broad temperature range of reactivity include:
A

 Lansteiner and Miller heat elution
 Weiner’s freeze–thaw method
 Lui’s freeze–thaw method and sonication

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14
Q
  1. Methods better suited for recovering warm-reactive alloantibodies or auto antibodies include
A

include use of organic solvents such as ether, zylene, methylene chloride, and chloroform or acids such as digitonin, citric, or glycine.

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15
Q
  1. Procedures that remove antibody but leave the red blood cells intact include
A

gentle heat, choloroquine, and acid glycine-EDTA methods.

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16
Q
  1. Preparation of a successful eluate can be influenced by several factors:
A

 Improper technique
 Inadequate stroma removal
 Insufficient washing of the sensitized red blood cells before eluting the antibody
 Incorrect method of transferring washed red blood cells
 Incorrect procedure used during the wash phase
 Use of saline to prepare eluates

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17
Q

Adsorption

A
  1. A technique used to remove an antibody or antibodies from plasma.
  2. Done most often to remove autoantibodies from a patient’s specimen in order to see if other antibodies are present in the plasma.
  3. Autologous adsorption and allogenic adsorption are the most common types used.
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18
Q

Adsorption

A

Is used to remove a antibody or antibodies from plasma

Done to remove autoantibodies to see if other antibodies are present In the patient plasma

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19
Q
  1. Autologous adsorption

cannot be used in the previous three months because the patient already has another type of red cell in his system

A

 The preferred method to remove autoantibodies.
 Cannot be used if the patient has been transfused within the previous 3 months because the patient’s specimen will also contain donor red blood cells.

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20
Q
  1. Allogenic adsorption

May be used when a patient with a autoantibody has been

A

Transfused

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21
Q
  1. Allogenic adsorption

Used either alone or paired with elution techniques to separate mixtures of

A

antibodies to allow for identification

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22
Q

 When choosing red blood cells for adsorption, the red cells that stimulate the most ___________ antibodies are considered.

A

Clinically significant

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23
Q

 Procedure requires a great deal of technical expertise because donor red blood cells adsorb both

A

autoantibodies and alloantibodies.

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24
Q

 Allogenic adsorptions run the risk of not detecting a

A

clinical significant antibody if a weakly reactive alloantibody is diluted or antibody to a high-frequency antigen is absorbed. Autoantibodies that are only partially absorbed may mimic the reaction pattern of alloantibodies.

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25
Q
  1. Rabbit erythrocyte stroma

Can be used to adsorb certain
Removes what antibodies
Plasma absorbed by this method should not be used for

A

 Can be used to adsorb certain antibodies.
 Removes cold autoantibodies and anti-B and antibodies in the P blood group system (anti-P1).
 Plasma adsorbed by this method should not be used for ABO typing.

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26
Q
  1. Rabbit erythrocyte stroma

Decreases the strength of or complexity removes other ___ from plasma including _________ significant antibodies

A

 Decreases the strength of or complexly removes other IgM antibodies from plasma, including clinical significant antibodies.
 Remains the adsorption medium of choice when an autoadsorption cannot be performed because a patient with a cold autoantibody has been recently transfused.
 Available in commercial kits.

27
Q

Titration

A technique used to measure the _______ of an antibody

A

Strength ( concentration)

28
Q

Serial dilution

A
  1. Serial dilutions are made of the antibody containing plasma and tested against selected red blood cells to determine the highest dilution causing a positive reaction. The result or titer is expressed as the reciprocal of the highest plasma dilution reacting 1+.
29
Q

Titer scores

A
  1. Titers can be resulted as a score, where a number is assigned to each positive reaction in the titration based on the strength of the reaction.
  2. The sum of these scores reflects the total binding strength of the antigen and antibody molecules (known as titration score or avidity).
30
Q
  1. Titration is most commonly used for determining
A

antibody activity and the potential severity of HDFN in alloimmunized pregnant women.

31
Q
  1. Titration can be a useful aid in identifying antibodies to certain
A

high-incidence antigens.

32
Q
  1. A titration can distinguish between a characteristic
A

high-titer, low-avidity antibody (HTLA) and a weakly reactive antibody with a low titer.

33
Q
  1. If the autocontrol or DAT is negative and the patient has been transfused or pregnant, then the reactions are likely due to
A

alloantibodies. Both combinations of multiple antibodies and a single antibody to a high-incidence antigen may cause this pattern of reactivity.

34
Q
  1. If the autocontrol or DAT is positive and the patient has not been transfused recently, then the results are likely due to an
A

autoantibody, either warm reactive, cold reactive, or both.

35
Q
  1. If the autocontrol or DAT is positive and the patient has been transfused recently
A

the results may indicate either an autoantibody or a delayed serological transfusion reaction.

36
Q

False postives may result from

A

Pan agglutination or rouleaux

37
Q

Multiple antibodies

  1. Certain combinations of antibodies may cause all or most cells tested to react
A

positively, making antibody exclusion and subsequent identification very difficult

38
Q

Multiple antibodies

A combination of techniques is usually required to identify

A

identify the specificity of each antibody present within a complex mixture of them. The technique(s) that should be used depend(s) on which antibodies are suspected.

39
Q

C. Antibodies to High-Incidence Antigens

A

Negative autocontrol but almost all positive Screen cells, panel cells, donor RBCs reacting +

40
Q

Antibodies to High incidence antigens

Testing with rare

A

Selected cells or plasma treated cells may confirm a + result

Knowning the patients Ethnicity may help

41
Q

Warm autoantibodies

A

Warm autohemolytic anemia

positive DAT, with screen, panel, and donor RBCs +

42
Q
  1. An antibody that causes all cells tested to agglutinate is called a
A

Panagglutinatin

43
Q

Patients with warm autoantibodies tend to have a increase risk of

A

Alloimmunization compared to the general Population

44
Q
  1. If the patient has not been transfused in the last 3 months, an ____________ can be performed and the adsorbed plasma tested for alloantibodies.
A

Autoabsorption

45
Q

Cold agglutinins

A

optimum reactivity between 37.7 and 77.0C

cause problems with a DAT because they can interfere with the detection of more clinically significant antibodies, and interfere with ABO typing

46
Q

Cold autoantibodies most common types

A

specificities to I, i, IT, IH, and Pr antigens; autoanti-I is the most common.

47
Q

Identify using

A

Cord and Adult RBCs

48
Q

good indicators of clinical significance for cold-reactive autoantibodies.

A

antibody titers and thermal amplitude studies

49
Q
  1. If cold autoantibodies may be masking alloantibodies, the autoantibodies can be removed from plasma by
A

autoadsorption using a low temperature or by adsorption with rabbit erythrocyte stroma.

50
Q

G. Cold Alloantibodies

  1. Include specificities such as
A

anti-M, anti-N, anti-P1, anti-P, anti-Pk, anti-Lea, anti- Leb, and anti-Lua.

they rarely cause in vivo hemolysis

you can eliminate the IS, test with Anti-IgG, or eliminate microscopic readings

51
Q

Prewarm technique

A

is used to eliminate the effect of Cold reacting auto and allo antibodies but it has show to show a 47% reduction in the performance in these antibodies

52
Q

Cold agglutinins are shown to be a concern in cardiac bypass surgery because

A

the patient is constantly in a state of hypothermia

Thermal amplitude and titer are a good indicator for potential complications

53
Q

If problems arise then the patient can be kept above

A

Body temperature or plasma exchange may be used to remove the cold autoantibody prior to surgery.

54
Q
  1. With a delayed hemolytic reaction the patient exhibits symptoms of
A

Hemolysis but with serological transfusion reaction the patient does not exhibit symptoms of hemolysis

55
Q

The reaction pattern will mimic a high frequency antigen but the cross match with donor red cells will be negative

A

Antibiotic: gentamycin, neomycin, and chloramphenicol
sugars: glucose
dyes acriflavine and tartrazine
Bacteriostatic/ antifungal reagents: paraben, thimerosal, sodium azide
Chemical: citrate, inosine, EDTA

56
Q

HLA antigens reactions

A

Febrile, nonhemolytic reactions, and can cause platelet refractoriness.

usually not clinically significant

Plt transfusions may be given to absorb the HLA antigens off the RBC

57
Q

Antibodies to low incidence antigens

A

Specificities include Wra, Kpa, Jsa, Cw, Dia, Goa, SC2, Mia, Lua, Cob, and Ytb. Typical patterns of reactivity
 The antibody screen is negative but one donor unit is incompatible if an IAT crossmatch is performed.

58
Q

Screen cells are

A

O in origin so A and B cells will not react

59
Q
  1. Anti-Sda and anti-Lua are characteristic of a
A

Mixed field reaction

60
Q
  1. Consent may be done at the time of admission or it may be obtained separately when the need to transfuse is identified.
A
61
Q

Transfusion request forms must be

A

Verbal or written and have the physician’s name and phone number, the date and time, the phone number, and have the number and amount of test ordered

62
Q

– ABO typing may be performed at least

A

twice before transfusing RBCs

63
Q

When selecting components for ABO typing

A

The components may be ABO compatible or ABO identical

Immunohematology - 4444 (17 decks)

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