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Immunohematology > Rh and LW Blood Groups > Flashcards

Rh and LW Blood Groups Flashcards

1
Q

Rh Positive

A

Presence of D antigen
Example: Group A+ means A blood type with Rh antigen
85% of population

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2
Q

Rh Negative

A

Absence of D Antigen
Example: Group O- means O blood type with no Rh antigen
15% of population

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3
Q

Discovery of D Antigen

A

1939-1943

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4
Q

Anti D

A

Described in HDN (Hemolytic Disease of the Newborn)

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5
Q

Anti-Rhesus

A

LW
Not the same as Anti D

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6
Q

Rh Gene

A

Chromosome 1
Autosomal Dominant

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7
Q

D antigen present

A

RBC only

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8
Q

D Clinical Significance

A

Second in significance
High Immunogenicity

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9
Q

Other Rh Antigens

A

Approx 50
5 most often seen - D, C, c, E, e

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10
Q

Wiener Nomenclature

A

Genes indicated by single letter
Gene product: agglutinogen
Gene product + subscript: haplotype
Factors: Individual antigens

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11
Q

Fisher Race Nomenclature

A

1 gene and 1 product per allele
Letter designations
Most often used

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12
Q

Tippet Theory

A

Two closely linked loci
Used in research

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13
Q

Fisher-Race Theory

A

Three closely linked loci inherited as a unit
Most common system

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14
Q

Wiener Theory

A

Single locus with multiple alleles
Most difficult

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15
Q

Rosenfield/Tippit

A

Antigens numbered in order of discovery/assignment to Rh system

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16
Q

Dosage Definition

A

Amount of antigen present on homozygous cell vs amount of antigen present on heterozygous cell (weak AHG rxn)

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17
Q

Genotype determination

A

Can estimate genotype based on reaction strength of phenotyping results

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18
Q

R2 cells

A

cDE - one haplotype
Stronger expression of D
React more strongly with anti-D reagent
Only scenario with enhanced antigen reactions

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19
Q

Cis Effect

A

Labilization of ligands that are cis to other ligands

20
Q

Cis Meaning

A

On the same side
Example: cDE - D and E are cist to each other
- E antigen produced by R2 gene (cDE) is weaker than E antigen produced by r” gene (cdE)

21
Q

Trans Effect

A

Comparison of antigens on both sides of the genotype

22
Q

Trans Meaning

A

On opposite sides
Example: C and E antigens are weaker in:
- R1(CDe)/R2(cDE) individuals C is trans with E but cis with D
- R1(Cde)/r(cde) - C is not cis or trans with either d, c, or e
- R2(cDE)/r(cde) - D is cis with E but no trans

23
Q

Possible Causes of Weak D expression

A

Due to Transmissible Gene Inheritance
- Less antigen sites
Positive Effect
- C gene in trans to D (weaker D antigen expression)
Partial D, D Mosaic, D Variant
- Lack a part of D antigen

24
Q

Weak D Notation

A

Du

25
Q

Weak D Clinical Significance for Donors

A

Weak D less immunogenic
- Weak D cells destroyed by anti D

26
Q

Weak D Clinical Significance in Recipients

A

Not necessary to test for weak D
- Receivin Rh neg blood doesn’t affect a person

27
Q

Cis Product Antigens

A

Ce (rhi) - R1 gene (CDe)

28
Q

Ce on same haplotye

A

CDE/cde does not produce Ce (rhi)

29
Q

c and e on same haplotye

A

cDE/CDe does not have f antigen

30
Q

G Antigen

A

Present on most D pos and all C pos cells
Appears to be anti C and anti D (cannot be separated)
Rh neg person can make anti-G to the G antigen

31
Q

Gene Deletions

A

Rare
Lack of activity at Cc and/or Ee sites
Cels may show very strong D activity

32
Q

LW Antigens

A

Present on most human RBCs
D neg cells have waker LW activity

33
Q

Anti LW

A

Reacts with D pos cells
Weakly with D neg cells

34
Q

Rh Null

A

Very Rare
No Rh antigens
Absence of Regulator Gene
RBC membrane abnormalitys
MUST transfuse with Rh Null Blood

35
Q

Rh Antibodies

A

Anti-D
Anti-C
Anti-c
Anti-E
Anti-e

36
Q

Rh Antibodies Result

A

Immunization (exposure)
Immunogenicity e<C<E<c<D

37
Q

False Positives in Rh Testing

A

Wrong reagent added
Contaminating Antibody
Polyagglutinable RBCs
Autoagglutinins/Abnormal Proteins (Multiple Myeloma)
Contaminated Reagent

38
Q

False Negatives in Rh Testing

A

Wrong Reagent Added
Reagent Not Added
Variant Antigen
Procedural
Weak Agglutination
Contaminated Reagent

39
Q

When is it necessary to use an Rh (D) control?

A

Using High protein anti-D reagent (albumin)

40
Q

What situations would cause a false positive reaction when doing Du testing?

A

Individual who has a positive DAT
Rh negative mother who has experienced a large fetal-maternal hemorrhage from Rh positive child

41
Q

What is the best way to elminate cell agglutination due to Wharton’s Jelly?

A

Wash cells multiple times (4-5)

42
Q

What are the possible causes of the following reactions:
patient cells + anti-D: 3+
patient cells + Rh control: 2+

A

Positive DAT
Rouleaux

43
Q

What are the possible causes of the following reactions:
patient cells + anti-D: 0
above tube + anti IgG AHG: 0
above tube + Coombs Check Cells: 0

A

Rh type cannot be determined
Inadequate washing of cells may have occurred
Inactive AHG reagent

44
Q

Rh testing and obtain the following results:
patient cells + anti-D: 3+
patient cells + Rh control: 3+
What is the next course of action?

A

Repeat the Rh typing with saline D or a chemically modified D antisera

45
Q

An 18 yr old female is admitted to ER following a serious accident. She has had no pregnancies, no history of transfusion, and is on no mediation. Her ABO/Rh testing:
patient cells + anti-A: 3+
patient cells + anti-B: 0
patient cells + anti-A,B: 3+
patient cells + anti D: 0 this tube + anti IgG AHG: 2+
patient cells + Rh Control: 0 this tube + anti IgG AHG: 0
Tube + CC: 2+
patient serum + A1 cells: 0
patient serum + B cells: 3 +

A

Patient is weak D positive, report as Rh pos

46
Q

Red cells type as weak D (Du) positive. The phenotype results follow. What is the most likely genotype?
Anti-C: 2+
Anti-c: 2+
Anti-E: 0
Anti-e: 2+

A

DCe/dce

47
Q

A patient is found to be Group O, Rh positive. They also have an anti-c in their serum. What is the most probable genotype of this patient? What type of blood must be transfused to this patient?

A

DCe/DCe; must be transfused with blood that is c negative

Immunohematology (17 decks)

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