BB Final Exam Review

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Describe the three mechanisms that result in weakened expression of the D antigen.

1. **Position Effect**: C in *Trans* to D; C is on opposite haplotype from D-steric arrangement (C interferes w/ D expression)
2. **Weak D**: Quantitative changes due to **fewer D antigen sites**
3. **Partial D or D Mosaic**: D Ag expression weakened when ≥1 D epitopes w/i the entire D protein is missing or altered. (possibility of making anti-D)

Direct Antiglobulin Testing detects in (vivo/vitro) sensitization of RBCs.

in **vivo** (body)

Indirect Antiglobulin Testing detects in (vivo/vitro) sensitization of RBCs.

in **vitro** (tube)

What is the purpose of **cross-matching**?

Determines compatibility of donor RBCs with recipient’s blood. (Ag’s on the donor cells, Ab on the patient serum/plasma)

What is the purpose of running an **autocontrol**? What does an autocontrol consist of?

1. Used to detect **autoantibodies** or **DAT +** cells
2. Patient’s serum/plasma + Patient’s own RBCs

What is the point of the “wash step” during IAT and DAT?

To remove any unbound antibodies that have the possibility of neutralizing the AHG and causing a false-negative reaction.

You just added **check cells** to your negative AHG reactions and __they agglutinated__. What does this tell us?

1. The test was adequately washed *prior* to addition of the AHG reagent.
2. AHG reagent *was added* to the test tube.
3. The AHG reagent that was added was in an *ACTIVE* form.

You just added **check cells** to your negative AHG reactions and they did __**NOT**__ agglutinate. What does this tell us?

* You may have forgotten to add AHG
* Your results are invalid
* Repeat the procedure with new AHG reagent and check the cell washer

When would you perform an **Extended Crossmatch**?

1. Patient history
2. At least one positive screen cell

* No history of antibodies
* SC+

Extended XM or Immediate Spin (IS) XM?

Extended crossmatch

* History of Anti-K
* SC=

Extended XM or Immediate Spin (IS) XM?

Extended crossmatch

* No history of antibodies
* SC=

Extended XM or Immediate Spin (IS) XM?

Immediate Spin (IS) XM

Given:

**Lele sese Hh AO**


1. What is the RBC phenotype?
2. What Antigen(s) would be secreted?

1. H, A, Lea+
2. Lea

Given:

**Lele Sese Hh BB**


1. What is the RBC phenotype?
2. What Antigen(s) would be secreted?

1. H, B, Le(a-b+)
2. H, B, Lea, Leb

Given:

**Hh or HH, Sese or SeSe, lele**


1. What is the RBC phenotype?
2. What Antigen(s) would be secreted?

1. H, Le(a-b-)
2. H

Given:

**Lele sese hh**


1. What is the RBC phenotype?
2. What Antigen(s) would be secreted?

1. Le(a+b-)
2. Lea

Given:

**lele sese AO or AA Hh**


1. What is the RBC phenotype?
2. What Antigen(s) would be secreted?

1. A, H, Le(a-b-)
2. none

__**Secretor Study**__

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saliva + anti-A + commercial A-cells → __**agglutination**__ (+ test)

\
What is your interpretation?

* No soluble A antigen present in saliva
* saliva is from a **non-secretor** of ABH

__**Secretor Study**__

\
saliva + anti-A + commercial A-cells → __**NO agglutination**__ (= test)

\
What is your interpretation?

* soluble A antigen present in saliva
* saliva is from a **secretor** of ABH

What anticoagulant is preferred for DAT?

EDTA

What are some possible causes of a positive DAT?

* Autoimmune HA
* HDN
* Drug-related
* Transfusion reaction
* Infusion of incompatible unit

What is the most common elution method used today?

Glycine acid

What are some drawbacks/cons of the **xylene elution method**?

* Flammable
* Carcinogenic
* Need to use in a ventilated area (hood)

What is an elution method best suited for eluting ABO antibodies?

Lui-Freeze Thaw

Which antibody class can cross the placenta? (IgG or IgM)

IgG

**Rh** **antibodies** belong to which antibody class?

IgG

What is the optimal reaction temperature for **Rh antibodies**?

37 C

Which blood groups show **dosage** on an ABID panel?

1. Rh
2. Duffy
3. Kidd
4. MNS

What phase does **Rh antibodies** react act?

AHG

What is Rhogam (RhIg)?

It’s a concentrate of predominantly **IgG anti-D** (RhIg) developed from pools of human plasma.

How does Rhogam work?

* Prevents mom from making immune anti-d by suppression of immune response.
* RhIg attaches to positive fetal red cells activating suppressor T-cells (current theory)

When do you give Rhogam?

* **Antenatal administration:** Given at 28 (to 32) weeks gestation to Rh negative pregnant women as long as the antibody screen is negative for anti-D.
* **Amniocentesis**: When an amniocentesis is preformed (16-18 weeks gestation) should receive full dose.
* **Postpartum administration**: When mom is Rh negative and has not produced anti-D and baby is Rh positive. Given w/i 72 hrs of delivery.

When do we run a **weak D**?

1. Obstetric patient
2. Donor units

How is **weak D** run?

1. Perform Rh typing on sample
2. Perform Weak D testing on Rh **negative** samples (of donor units or obstetric pt)
3. Incubate tube (Anti-D + patient cells\[same tube from your Anti-D typing\]) at __**37 C**__ for 15-30 min
4. After incubation, wash 3-4x in cell-washer
5. Add **2 drops of AHG** reagent
6. Spin/read

What do you do next when a **weak D** test is positive? Why?

Run DAT because you want to make sure that the reaction is a *valid* reaction and not just due to the red cells being coated by an antibody.

What antibody class does the **Kell** blood group belong to?

IgG

What is the optimal reaction temperature for **Kell**?

37 C

What phase will **Kell** react at?

AHG

K is *highly* immunogenic and often associated with DHTR. (True/False)

True

What are the antigen frequencies for **K** and __**k**__ respectively?

1. 9%
2. 91%

Kell null cells can be made with treatment by _____ *,* _____ *or* ______.

2-ME, DTT or ZZAP

What phenotype is resistant to malaria?

Fya-b-

Duffy blood group is __destroyed__ by enzyme treatment. (True/False)

True

What are the antigen frequencies for **Fya** and **Fyb** respectively?

1. 65%
2. 80%

What antibody class does the **Kidd** blood group belong to?

IgG

What is the optimal temperature that **Kidd** will react at?

37 C

What phase will **Kidd** react act?

AHG

What effect does enzyme treatment have of **Kidd** antibodies?

Enhanced by enzymes

What does **Anti-Jk3** mean?

Patient will be Jka-b-

What are the frequencies for **Jka** and **Jkb** respectively?

1. 77%
2. 72%

Why are **Kidd antibodies** implicated in delayed transfusion reactions?

Titer drops below detectable levels very quickly

What are some diseases associated with **Kell**?

1. McLeod Phenotype (decreased RBC survival)
2. Chronic Granulomatous Disease

What antibody class does **Lewis** blood group belong to?

IgM

What is the optimal reaction temperature for **Lewis**?

Most often 4 C, sometimes 37 C

If **Lewis** is reactive at room temperature, it is clinically significant. (True/False)

False

What phase does **Lewis** react at?

RT, 37 C, and AHG

What effect does enzyme treatment have on **Lewis antibodies**?

Enhanced by enzymes

**Lewis** can be neutralized. (Treu/False)

True (saliva)

Why is **Lewis** not implicated in HDFN?

Lewis antigens are poorly developed at birth (cord cells are Lea-b-)

What are the frequencies of **Lea** and **Leb** respectively?

1. 22%
2. 72%

What antibody class do **MN** belong to?

IgM

What antibody class does **S** belong to?

IgG

What is the optimal reaction temperature for **MN**?

4 C or 37 C

What phase does **MN** react at?

IS, 37 C, and AHG

What effect does enzyme treatment have on **MN**?

Destroyed by enzymes

What can be done to enhance **Anti-M** reaction?

Acidify pH

What is the optimal reaction temperature for **S**?

37 C

What phase does **S** react at?

AHG

What effect does enzyme treatment have on **S**?

variable

Is **S** blood group clinically significant?

Yes

What are the frequencies for **M, N,** **S** and **s** respectively?

1. 79%
2. 70%
3. 55%
4. 90%

List the IgM antibodies

1. anti-I, -H
2. anti-M
3. anti-N
4. anti-P1
5. anti-Lea
6. anti-Leb

What are the IgG (clinically significant) antibodies?

1. anti-D
2. anti-C, -__c__
3. anti-E, -__e__
4. anti-M (some)
5. anti-K, -__k__
6. anti-Fya, -Fyb
7. anti-Jka, -Jkb
8. anti-S, -__s__

What antibody class does **P** blood group belong to?

IgM (Anti-P1)

What is the optimal reaction temperature for **P**?

4 C

What phase does **P** react at?

IS, 37 C, AHG

What effect does enzyme treatment have on **P**?

Enhanced by enzymes

Anti-P1 can be neutralized by ______.

Hydated cyst fluid

Is Anti-P1 clinically significant?

No

Donath-Landsteiner antibody

Autoanti-P

What antibody class does **Ii** blood group belong to?

IgM

What is the optimal reaction temperature for **Ii**?

4 C

What phase does **Ii** react at?

IS and occasionally 37 C

What effect does enzyme treatment have on **Ii** antigens?

Enhanced by enzymes

**Ii** is not clinically significant. (True/Fasle)

True

A strong **Anti-I** reaction is associated with which bacteria?

*Mycoplasma pneumonia*

**Anti-i** is associated with which disease?

Infectious mononucleosis

ABID rule out instructions

1. Match anagram to panel by lot #
2. Use only cells that have a __negative__ reaction
3. **Dosage**: use a __homozygous__ cell only
4. Rule of 3

If a patient has an antibody to a __high incidence antigen__ and needs some blood, where would they find it?

* Sibling
* Rare donor file

What is a **high incidence antigen**?

Antigens that occur in greater than 99% of the population.

If a patient has an antibody to a __low incidence antigen__ and needs some blood, where would they find it?

Random donors

What is a **low incidence antigen**?

These antigens occur in less than 1% of the population.

What is the purpose of **phenotyping**?

To confirm the antibody that was found

What is the equation for **screening units**?

(# of Units Requested)/(frequency of __**Antigen negative**__ in population)

__**ABO Discrepancy**__

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**Weak/Missing Antibody (isoagglutinin)**

\
* What are the causes of this discrepancy?

* Elderly
* Newborn
* Immunosuppressed (Leukemia, Hypogammaglobulinemia)
* BMT
* Congenital immunodeficiencies

__**ABO Discrepancy**__

\
**Weak/Missing Antibody (isoagglutinin)**

\
* How would you resolve this discrepancy?

* Incubate @ RT for 30 min.
* Incubate @ 4 C for 30 min.
* Adsorption/Elution

__**ABO Discrepancy**__

\
**Weak/Missing antigen**

\
* What are the causes of this discrepancy?

* Subgroup of A or B
* Disease state (leukemia)
* BMT

__**ABO Discrepancy**__

\
**Weak/Missing antigen**

\
* How would you resolve this discrepancy?

* Incubate @ RT for 30 min.
* Incubate @ 4 C for 30 min.
* Adsorption/Elution

__**ABO Discrepancy**__

\
**A B D** __**interp**__ **A1 cells B cells** __**interp**__

4 0 4 __A pos__ 1 4 __O__

**Extra reaction in the reverse**

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* What are the causes of this discrepancy?

* Subgroup of A
* Cold Alloantibody
* Cold Autoantibody

__**ABO Discrepancy**__

\
**Extra reaction in the reverse**

\
* What is run next to determine the cause?

1. O cells
2. A2 cells
3. Autocontrol (pt plamsa + pt RBCs)