Blood Bank Final Exam

Phenotype O frequency

45%

Phenotype A1 frequency

32%

Phenotype A2 frequency

8%

Phenotype A1B frequency

3.2%

Phenotype A2B frequency

0.2%

Respective sugar and enzyme for A

N-acetylgalactoseamine sugar and N-acetylgalactoseamine-transferase 

Respective sugar and enzyme for B

galactose sugar and galactosyl-transferase

Respective sugar and enzyme for H

Fructose sugar and furctosyl-transferase

What genes are not present at the H locus in the Oh phenotype

A,B and H

What are the two methods to determine the actual ABO genotype or Phenotype for Oh

Anti-H lectin and family studies

What is the ABH red cell antigen expression for the Oh phenotype

no expression

What is the expected serum alloantibody activity for the Oh phenotype

strongly reacting allo-anti H ad naturally occurring in addition to anti-A, anti-B, and anti-A,B

What is the phenotype is expressed in Oh

Bombay phenotype hh

What is the immunoglobulin class of naturally occurring antibodies

IgM

What is the origin of ABO antibodies

environmental(IgM), mistransfusions, pregnancy, vaccinations(IgG)

What is the development of ABO antibodies

detectable around 3-6 months old, higher titer around 5-10yrs old, and elderly has the lowest titer

what is the predominate immunoglobulin class for ABO antibodies

Anti-A and Anti-B (IgM)

What is the in vitro serologic reactivity of ABO antibodies

room temp, IS, saline reaction, can bind complement(causing hemolysis) through agglutination

What is the clinical significance of ABO antibodies

hemolyica transfusion reactions(small amount of ABO incompatible blood will cause acute HTR) and hemolytic disease of thefts/newborn

Forward grouping

front type, reagent antisera is a known antibody, used to determine the patient's red blood cells' unknown antigen 

Reverse grouping

back type, patient serum is unknown antibody and is used to determine the reagent RBCs known antigen 

Type specific

transfuse a group A with a group A, and O with O, etc..

Type compatible

Transfuse a group a group AB with group A or a group B with group O 

Type incompatible

never transfuse a group O with anything except group O, never give group A to B or B to A 

Anti-A1 lectin

dolichos biflorus 

Anti-H lectin

Ulex europaeus 

Bombay phenotype(Oh)

homozygous amorphic genotype 

Immune antibody

An antibody that is produced only after deliberate exposure to a foreign antigen

Precursor substance

A basic or “parent” antigenic structure on red blood cells that can be modified by enzymes to form more specific antigens

Subgroup

A variant form of a blood group antigen, often with weaker expression or slightly altered serologic characteristics

universal donor

Type o negative

universal recipient

Type AB positive

Partial D mechanism of production

Incomplete D antigen- actually missing part of antigen and may type weaker than expected but still detected without IAT

Genetic D mechanism of production

Inheritance of D genes that code for weakened expression of D antigen usually due to Ro gene, more common is AA pop

Position Effect D mechanism of production

D antigen is weakened when C is “trans”to D(usually with the r’ gene) 

Clinical significance of the Weak D phenotypes in donors and blood recipients.

Can cause Immune production of an Anti-D

Rh system  predominant immunoglobulin class

IgG

Rh system stimulus for production

unexpected antibodies

Rh system ability to bind complement

does not bind C’

Rh system clinical significance

Cause HTR and HDFN

Rh system characteristic serologic reactivity

immunogenicity (D>c>E>C>e) 

purpose of Rh control

severs as a negative control for D testing that detects interference from unexpected antibodies coating the cells 

Rh control composition

high protein reagents

Rh contorl expected results

negative(valid results)

Blood group system

groups of antigens on the red cell membrane that share related serologic properties and genetic patterns of inheritance  

chromsome

gene-carrying structure  

allele

a specific location on a chromosome where a gene resides and may be occupied by one or several genes 

gene

 a segment of DNA that codes for a particular protein; it its the basic unit for inheritance of any trait  

gene locus

specific physical location of a gene or DNA sequence on a chromosome  

trait

 characteristic of an organism that can be observed or measured, which is influenced by genes  

antithetical partner

antigens/allelic partners  

linked genes

when two genes, located closely on the same chromosome, do not assort independently, they are said to be “linked”  

crossing over

occurs when genes not closely linked “cross over” and exchange genetic information. Genes that are closely linked aren’t affected  

amorphic

a silent gene

X-linked

inheritance pattern that only resides on the X chromosome 

dosage effect

number of copies of a gene (gene dosage) directly influences the expression or intensity of a trait 

gene interaction

​​where the effect of one gene is altered by the presence of another gene, a gene gets modified or suppressed 

anamnestic response

remembered response 

sensitization stage

primary stage of Ag-Ab reactions

visualization stage

secondary stage of Ag-Ab reactions 

affinity

 strength of a single Ag-Ab bond

avidity

combination of affinities

specificity

ability of an antibody or test to recognize and bind only to its intended antigen

cross reaction

antibody reacts not only with its intended antigen but also with a structurally similar, unintended antigen

zone of equivalence

 Ag and Ab are in optional concentration, insoluble lattice structure

prozone

excess of unbound Ab

post zone

excel of Ag binding sites

Peer review Examples

AABB- Association for the Advancement of Blood and Biotherapies, CAP- College of American Pathologists

State review example

Indiana State Department of health

federal review example

FDA

phenotype

the observation of detectable traits; the outward expression of genes

genotype

an individuals genetic makeup

public antigen

high-frequency genes

private antigen

low-frequency genes

dominant

trait is seen anytime the gene is present, regardless of the zygosity of the gene 

recessive

is seen only when the gene is present in a homozygous state

codominant

equal expression of two inherited genes

cis position

genes on the same chromosome (CDe/cde) 

trans position

genes on homologous chromosomes (Cde/cDe)

Individual acquires his blood group genes according to Mendel’s Laws of  Inheritance

Each parent contributes half of the inheritance, and individual traits are inherited independently of each other 

pattern of inheritance most blood group systems follow

Codominance

direct exclusion

 offspring possesses a trait that neither the mom the alleged dad possesses 

Indirect exclsion

offspring does not possess a gene that should have been inherited 

type of cells responsible to produce antibodies

B-cells

Primary stage

initial binding of Ag and Ab 

Secondary stage

observable stage(agglutination, precipitation, C’-fix) 

Tertiary stage

In vivo biologic expression of Ag-Ag rection or the immune response

primary response

large dose, long latency period(10 days-months), IgM produced and then IgG 

Secondary response

Smaller dose, shorter latency period(1-2days), IgG produced and very small IgM 

 Immunogenicity

is the ability of an antigen to stimulate an antibody response. Because of differences in immunoglobins not all blood group antigens are equally immunogenic in vivo 

main components that make up the red cell membrane.

Proteins(52%), Lipids(40%), Carbohydrates(8%)

Explain how the zeta potential effects the Ag-Ab reaction

 Net charge and distance between the Ag-Ab affect the zeta potential

Explain the purpose of using enhancement media in antiglobulin tests.

Allows Ag and Ab to come closer together and reduces incubation time

Albumin enhancement media

collieded/high protein made media tat reduced ionic cloud

 LISS- Low Ionic Strength Solution

reduced ionic cloud to bring cells closer together  

PEG – Poly Ethylene Glycol

removes H2O and increases antibody concentration  

 Enzymes – Ficin, Papain, Bromelin

Cleaves some of the membrane’s glycoproteins, destroying some antigens, while exposing others

EDTA tubes

Purple pink, plasma sample

chelates Ca+ ions which prevents activation of the classical complement pathway

no complement activity in sample

Clot Tube

red top, serum sample

Component present in ‘fresh’ sample and C’ remains active for 24-28 hrs and stored at 4 °C

can be used to detect complement-dependent antibodies

Antigen known testing sources

manufacturer screening, panels, and A & B cells