blood 1.5

Fisher- race: number of principle genes in system

8 gene complexes

Fisher-race: number of genetic loci involved

3 distinct loci

Fisher-race: nomenclature

DCE

Wiener: number of principle genes in system

8 majore genes

Wiener: number of genetic loci involved

1 large loci and 3 sub loci

Wiener: nomenclature

Rh-Hr

State the frequency of the D,C,E,c and e antigens in the US Caucasian population

D = 85%

C = 70%

E = 30%

c = 80%

e = 98%

Rh system antigens: development on newborn erythrocytes

Fully developed at birth

Rh system antigens: Chemical composition

Lipoproteins

Rh system antigens: Location in the body

Only on RBC membrane

ABO system: development on newborn erythrocytes

Not fully developed at birth

Only ¼ - ½ the # of Ags as adult RBCs

ABO system: chemical composition

Sugars added to basic glycosphingolipid (precursor substance)

ABO system:location in body

Everywhere

Partial D of Weak D phenotype: mechanism of production

Incomplete D-antigens (missing part)

Partial D of Weak D phenotype: Ability of the phenotype to be transmitted genetically

Can be passed from gen. to gen.

Partial D of Weak D phenotype: In vitro serologic reactivity

Weaker then expected but still detected without IAT

Partial D of Weak D phenotype: Ability of produce anti-D

May develop anti-D for missing part

Genetic of Weak D phenotype: mechanism of production

Inheritance of D genes that code for weakened expression of D antigen

Genetic of Weak D phenotype: Ability to be transmitted genetically

Can be passed to next gen

Genetic of Weak D phenotype: In vitro serologic reactivity

Requires the IAT to be detected (not very reactive)

Genetic of Weak D phenotype: Ability to produce anti-D

No anti-D produced

Position of Weak D phenotype: mechanism of production

Dxantigen weakened when C is trans to D

Position of Weak D phenotype: Ability of the phenotype to be transmitted genetically

Lost in next gen

Position of Weak D phenotype: In vitro serologic reactivity

Rarely seen because anti D anti sera is too strong

Position of Weak D phenotype: Ability to produce anti-D

No anti-D produced

Which Rh genotypes are most likely to test as Rh positive by weak D testing only

any with little d (r)

Clinical significance of the Weak D phenotypes in donors and recipients

Donors must be tested for weak D and labeled as D positive if tested as weak D positive

If weak d not tested assume patient is negative and only give Rh = blood

Clinical and lab findings for an individual classified as Rhnull

Lack all Rh antigens (D,C,E,c,e)

“Leaky” membrane

Stomatocytes (increase retics, decrease H & H, increase OF)

Transfuse with Rh null RBCs only

Describe G Rh antigens

Present on most D positive and all C positive RBCs

Anti- G will react with anti-A,B

Anti-G only made by people who are neg. for both C and D

Describe deletions/enhanced D

Lack Cc and/or Ee

Strong D antigens

Incest marriage

Rh system antibodies: predominant immunoglobulin class

IgG

Rh system antibodies: Stimulus for production

RBC stimulated → unexpected antibodies

Rh system antibodies: Ability to bind complement

Does not

Rh system antibodies: Clinical significance

Must “honor” findings, if it is Rh= is found must give negative blood for transfusion

Rh system antibodies: Characteristic serologic reactivity

Reactivity is greatly enhanced when cells have been enzyme-treated

Rh system antibodies: Transfusion practices

Try to give Rh specific when possible

Rh= blood is ok to give to Rh= patient anytime (universal donor)

Rh+ only okay to give to Rh= patient in emergencies

Never give Rh+ to Rh= female of child bearing age

Procedure for testing for the D antigens including for weak D antigen

Anti-D reagent + cell suspension

• spin and read

  • Positive

  • Negative → report neg or proceed w/ weak d

Use of Rh control: purpose of use

Serves as a negative control for D testing

Use of Rh control: Composition

Diluent of anti-d without antibody in it

Use of Rh control: Expected results

Negative

Use of Rh control: Troubleshooting required when expected results not obtained

Restart/repeat

Causes for false positives for Rh typing

1. Cold auto agglutinins

2. Warm auto agglutinins

3. Positive DAT on cells

4. Rouleaux

5. Using wrong antiserum

6. Using post-transfusion sample of an Rh= who gets Rh+ blood

Causes of invalid D typing at the immediate spin and AHG phases of testing

Define: “cis” position

on same allele

Define: compound antigens

Antibodies only react when both antigens are on the same allele

Ex: f(ce)

Define: “trans” position

On different alleles