blood 1.4

State Caucasian frequencies of 6 common phenotypes in ABO System

1. O = 45%

2. A1 = 32%

3. A2 = 8%

4. B = 11%

5. A1B = 3.2%

6. A2B = 0.8%

H system + ABO genes to determine the blood group A,B,AB, O and Oh phenotypes

h-gene almost universally present

paves the way for ABO to express themselves as antigens on RBC surface

all groups except Oh have H antigens

Genetic pathway for expression of ABO and Hh system antigens

look at slide for this

Respective enzyme and immunodominant sugars responsible for A,B and H specifically

A antigen:

• N-acetygalactoseamine sugar

• N-acetygalactoseaminyl-transferase

B antigen:

• galactose sugar

• galactosyl-transferase

H antigen

• fructose sugar

• frucosyl-transferase

Predict the strength of reactivity with anti-H for various ABO phenotype

(most H) O>A2> B> A2B> A1 > A1B (least H)

• tested using Anti-H lectin

Explain how ABH and Se genes interact to form

• A, B or H sugar attaches to either forms of the PS (RBC antigens can only attach to PS2)

• Presence in secretions depends on inheritance of Se gene

• Se arises a form of fructosyl-transferase that acts primarily on type-1 PS

List secretions in which ABO soluble antigens can be found

1. Saliva (main one)

2. tears

3. sweat

4. urine

5. digestive juices

6. amniotic fluid

7. breast milk

8. seminal fluid

9. pleural

10. serum (as glycoprotein)

Distribution of ABO antigens in tissues

1. RBC membrane

2. WBC

3. PLT

4. Skin cells

5. sperm

6. cornea

7. cells of amniotic fluid

8. endothelial cells

O_h Phenotype w/ respect to: genes present at H locus

no H gene, A and B may be present but do not work

O_h Phenotype w/ respect to: two methods to determine actual phenotype

1. Anti-H lectin

2. Allo-anti-H

3. family studies (genotype)

O_h Phenotype w/ respect to: ABH red cell antigen expression

No A, B, AB or H antigen present (has all four antibodies)

• will always “appear” to be group O

O_h Phenotype w/ respect to: Phenotype expressed

“group” O

O_h Phenotype w/ respect to: expected serum alloantibody activity

very strong allo-anti-H activity

O_h Phenotype w/ respect to: blood selection for transfusion

only blood from another O_h

Immunoglobulin class of “naturally occurring” antibodies

ABH antibodies

Reciprocal relationship b/w ABO RBC antigens and serum antibodies of blood groups (Landsteiner’s rule)

Antigen + specific antibody = reaction

• Antigen present = antibody absent

• Antigen absent = antibody present

ABO antibodies w/ respect to: Origin

formed in response to environmental stimuli

ABO antibodies w/ respect to: development

At birth = none

5-10 year olds = higher titer then decreases over years

Elderly = low to absent titer

ABO antibodies w/ respect to: predominate immunoglobulin class

IgM

ABO antibodies w/ respect to: in vitro serologic reactivity

optimal temp = room temp or colder

immediate spin reactions

can bind complement (not usually anymore due to EDTA)

ABO antibodies w/ respect to: Clinical significance

Causes both

• Hemolytic transfusion reactions

• Hemolytic disease of Fetus/newborn

Forward grouping

Reagent Antisera

• Known antibody

Patient RBC

• unknown antigen

clumping means it is that

Ex: anti-A clumps = Type A

Reverse Grouping

Patient Serum

• unknown Ab

Reagent RBC

• Known Ag

Clumping means the opposite is true

Ex: A1C clumps = Type B

Type Specific

Everything is the exact match for patient

Type Compatible

Close enough match to where it won’t cause major issues

Type incompatible

Does not match the patient at all

RBC Compatibility

Loot at chart

Plasma Compatibility

Look at chart

Define: amorphic gene (silent gene)

Silent gene, has no detectable product

Define: anti-A1 lectin

Differentiate A1 from A2

Define: anti-H lectin

Differentiates between A1 and A2

Differentiates between O and Oh

Define: Bombay phenotype (Oh)

Have no A,B or H antigen present

Define: forward ABO grouping

Known antibody and unknown antigen(RBC)

Define: immune antibody vs naturally occurring antibody

Immune antibody:

• Come from mother

Naturally occurring:

• ABH antibodies

• Come from outside the body

Define: precursor substance

ABH antigens are sugars added to a basic glycosphingolipid

• make H substance

Define: Reverse ABO grouping

Known antigen (RBC)

Unknown antibody (serum)

Define: secretions

Come from Se gene

If inherited, can determine ABO type from secretions like saliva

Define: subgroup

Define: universal donor

O-

Define: Universal recipient

AB+