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BMS 185 Lecture > Quiz 6 > Flashcards

Quiz 6 Flashcards

1
Q

What do you do when an antibody screen is positive? Why?

A
  1. Antibody Identification
    2a. to avoid patient hemolytic transfusion reactions
    2b. to detect and monitor patients at risk of delivering infants with Hemolytic Disease of the Fetus and Newborn (HDFN)
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2
Q

What type of antibodies attack RBC antigens?

A
  1. Alloantibodies
  2. Naturally occurring antibodies
  3. Autoantibodies
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3
Q

Who is required to take an antibody screen?

A
  1. Blood Donors
  2. Transfusion Recipients
  3. Obstetric Patients (Pregnant Moms for HDFN and RHIG[Rh immune Globulin])
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4
Q

What is the antibody screen test tube method?

A

Patient’s serum or plasma is mixed with RBC’s that have known antigen content

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5
Q

How do you perform the antibody screen test tube method?

A
  1. Mix patient serum/plasma + RBC w/ known antigen
  2. Immediate spin phase
  3. 37C incubation
  4. Add enhancements (optional)
  5. Centrifuge and then read for hemolysis or agglutination at 37C
  6. Wash 3-4x
  7. Add AHG, centrifuge, and read at AHG
  8. If all are negative, add check cells
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6
Q

How are check cells made?

A

Rh+ RBCs coated w/ Anti-D antibodies

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7
Q

What do check cells check for?

A

Checks if you added Coombs serum and/or if you washed the RBCs properly

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8
Q

Are antibody screens direct or indirect testing? Why?

A
  1. INDIRECT
  2. Antibodies will not bind/coat the RBC in vivo. Only coats in vitro
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9
Q

Would hemolysis be considered a positive or negative reaction?

A
  1. Positive
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10
Q

If hemolysis is present, what do you write in?

A

“H”

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11
Q

What are screening cells?

A

2-3 different donors that are group O w/ at least one cell grp antigen present

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12
Q

Why are homologous expression preferred for RBC reagents over heterozygous (in antibody screens)?

A
  1. Homologous expression will show a stronger reaction.
  2. If the patient is has heterozygous expression, a heterozygous RBC reagent’s titer may be too low. There will be little to no reaction and will be misread.
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13
Q

What are some enhancement reagents?

A

22% albumin, Low Ionic Strength Solution (LISS), Polyethylene Glycol (PEG)

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14
Q

What does 22% albumin do?

A

reduces zeta potential
(due to diff. in electrical potential and reduces negative charge)

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15
Q

What does Low Ionic Strength Solution (LISS) do?

A

Lowers zeta potential and increases uptake of antibody onto the rbc (increases sensitization)

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16
Q

If you add Low Ionic Strength Solution (LISS) as an enhancement reagent, you have to read

A

MICROSCOPICALLY IF NOT VISIBLE MACROSCOPICALLY!!!!

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17
Q

If you add Polyethylene Glycol (PEG) as an enhancement reagent, you cannot read at ____. You must only read _____

A
  1. 37C
  2. MACROSCOPICALLY at AHG
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18
Q

What does Polyethylene Glycol (PEG) do?

A

reduces H2O conc., increases antibody conc.

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19
Q

If this C3b if converted to C3d, what happens? Why?

A
  1. RBCs are protected from hemolysis.
  2. Macrophages have receptors for C3b, but not C3d.
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20
Q

What is in polyspecific AHG?

A

antibodies for both IgG and Complement

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21
Q

What is in monospecific AHG?

A

antibodies for EITHER IgG OR Complement

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22
Q

Some rare anti-jk AB can only be detected by complement they bind to, so they can be missed by _________ IgG AHG. Monospecific or Polyspecific IgG?

A

monospecific

23
Q

How do you do an antibody screen w/ gel methodology?

A

Differences: Microtubules w/ dextran acrylamide gel (anti-IgG in gel), 0.8% conc. of Screening cells in LISS
1. Add patient’s plasma/serum and 0.8% LISS Screening cells to reaction chamber above the gel
2. Incubate card at 37C for 15-60 minutes for possible antibody sensitization
3. Centrifuge the card to allow RBCs to sink into the gel
4. Agglutinated cells will have trouble sinking to the bottom (4+ at the top, 0 at the bottom)

24
Q

What is an advantage of antibody screen w/ gel methodology?

A
  1. No washing
  2. No coombs control steps
25
Q

What does a 4+ look like in antibody screen w/ gel methodology?

A

One big button at the top

26
Q

What does 3+ look like in antibody screen w/ gel methodology?

A

Agglut. cells at the upper half of the gel

27
Q

What does 2+ look like in antibody screen w/ gel methodology?

A

Agglut. cells the whole length of the gel

28
Q

What does 1+ look like in antibody screen w/ gel methodology?

A

Agglut. cells at the lower half of the gel

29
Q

What does 0+ look like in antibody screen w/ gel methodology?

A

all pellet at the bottom

30
Q

If there is agglutination at room temp (IS), what type of AB is it? What are some examples?

A
  1. IgM antibodies
  2. anti-P1, anti-N, and anti-I
31
Q

If there is agglutination at AHG phase, what type of AB is it?

A

IgG

32
Q

What is a autologous control? Normally, it should be negative or positive?

A
  1. Patient RBC against Patient Serum/Plasma
  2. Negative
33
Q

If a patient has a positive antibody screen and a negative autologous control, what is likely to be present?

A

alloantibody (naturally occurring antibody against foreign cells/tissues)
Note:
- check if patient has been pregnant or transfused in the past 3 months

34
Q

If a patient has a positive antibody screen and a positive autologous control, what is likely to be present?

A

autoantibody (naturally occurring antibody against self cells/tissues)

35
Q

Does a single antibody act at the same/different phase and strength?

A

SAME phase and strength! unless it shows dosage

36
Q

Do multiple antibodies act at the same/different phase and strength?

A

DIFFERENT phase and strength

37
Q

If there is hemolysis present at antibody screen, what can be present?***

A

anti-Vel, anti-Tja, and anti-H (Bombay)

38
Q

If there is mix field present at antibody screen, what can be present?***

A

Anti-Lu(a)

39
Q

When should you suspect rouleaux?

A

any patient plasma/serum tests that have a reaction

40
Q

what do you do if rouleaux is present? (solving)

A

saline replacement technique

41
Q

At what phases do you read an antibody identification panel?

A

IS, 37C, AHG

42
Q

What is important to know about the patient when reading an antibody identification panel?

A

Age, Sex, Race, Medications/Health Conditions, Pregnancy/Transfusion History, etc.

43
Q

What are some possibilities of DAT/autocontrol being positive?

A
  1. Autoimmune disorder
  2. Medication
  3. Pregnancy
  4. Transfusions
44
Q

If someone who had a transfusion/pregnancy, in the last 3 months, has a positive DAT/autocontrol result… why is it possibly dangerous?

A

may have a delayed hemolytic transfusion reaction due to alloantibody (natural AB against foreign body

45
Q

What ABO group are screening cells?

A

grp O

46
Q

What do you rule out in antibody identification panels?

A
  1. RBCs with all Negative RBC Reaction
  2. (all neg.) cross out homozygous expression (ex. 0,+)
47
Q

How do you evaluate panel results?

A
  1. What phase(s) and strenth(s) did the +ive reactions occur? If different there can be,
    1a. More than 1 antibody
    1b. 1 antibody showing dosage
    1c. Antigen w/ variable expression
48
Q

T or F, Strength of reaction DOES demonstrate antibody significance.

A

False, strength does not mean anything for AB significance

49
Q

If a single __-antibody is present in an antibody id panel, it matches a pattern of antigen expression exactly

A

allo(antibody)

50
Q

When would you use select cell panels?

A
  1. when you have ruled out all common antibodies
  2. when you have a known antigen and you want to see if there are any additional unknown antigens
51
Q

What if every cell panel reacts with a…
1. Positive Autocontrol?
2. Negative Autocontrol?
3. just they all react..

A
  1. Pregnant/Transfusion (mixed field)
  2. Alloantibodies against high prevalence antigens (equal strength!)
  3. Multiple alloantibodies
52
Q

When would you do an autoadsorption/alloabsorption (remove autoantibody/alloantibody)?

A

If there are 2 alloantibodies present and one is stronger than the other.
Basically one has a stronger reaction than the other alloantibody, so you have to remove the stronger one to be able to see the 2nd alloantibody

53
Q

What do you need as evidence to prove a suspected antibody? (95% probability)

A
  1. Three antigen POSITIVE cells w/ agglut.
  2. Three antigen NEGATIVE cells showing no reaction

BMS 185 Lecture (11 decks)

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