Week 3 Flashcards
(37 cards)
What are Co-Dominant Alleles
The product of each allele is expressed
Equal expression of 2 different inherited alleles
What are Dominant Alleles
Expressed even in a Heterozygous
state
when one gene product is expressed over another
What are Recessive Alleles
Expressed in a Homozygous state
recessive alleles are only expressed in a homozygous state
only expressed when inherited by both parents
What is the dosage effect
- AB reaction strength depends on the quantity of target antigen present on a target RBC
Kidd blood group system; alleles are codominant, meaning that the product of each allele is expressed
Jka and Jkb
-the more binding sites that are present the stronger the reaction
-stronger agglutination grading when RBC AG are expressed in homozygous form
-identified with ABs associated with Duffy, Kidd, Rh MNs group
What does phenotyping describe
which antigens are present on the red cell and determined through
serological testing. Positive indicates that antigens are present. A negative indicates that the antigens are not present.
What are the duffy AG
Fya and Fyb
How can Enzymes affect reactions with Ag
-enhance, suppress, and inhibit entirely the antigen reactivity with the antibody.
-Ficin, Trypsin, Papain, and Bromelin are examples of the proteolytic enzymes used.
* Removes the net negative charge on red cell membranes and denaturing the antigenic determinants.
* Reduces the Zeta potential and enhances the agglutination of some other antigens.
-Duffy and MNS are destroyed by the enzyme-treated cells, but Kidd Rh and Lewis blood group systems are enhanced by enzyme-treated cells. Kell has no effect.
Where can ABO AG be found
-RBC, endothelial cells, platelets,
lymphocytes, epithelial cells, and tissue cells. If the secretor gene is inherited, ABO antigens can be found in body fluids such as saliva.
The ABO-H-Link
-Before A/B sugar is added to precursor , L-Fucose needs to be added
-H gene codes for enzyme FUT 1 to add the
L-Fucose (sugar) to the precursor substance.
-this forms the H ag which is needed for the expression of A and B AG since gene produces of ABO alleles need H AG to be the acceptor molecule from A & B transferases
H Gene
-codes for L-fucosyltransferase, which adds the L-fucose to the precursor substance to
produce the H antigen.
-H Locus has 2 significant alleles: H and h
- little h allele is considered an amorph with a rare frequency, does not code for enzyme and is the silent h
-hh is rare
What is the bombay phenotype
- hh genotype
-no fucose added to precursor
-no A or B sugar can be added
-group like its a group O and serum contains Anti-A, Anti-B and Anti-A,B, and even Anti-H.
Why is Anti H important
-antibody is capable of high thermal activity and complement activation, which results in hemolysis.
how to detect Bombay in the lab
-bombay phenotype is Oh
-pt have Anti H so they react with all cells except rbc from other bombays so if they need a transfusion it has to be from another bombay
-reaction strength depends on number of H ag on the cells
-pf types as group O and the AB screen would positive across the whole panel
-
slide 19
What is the lewis system
-Ag are not produced on the RBC membrane
-not intrinsic
-produced and secreted on Type 1 precursor chains and then absorbed onto RBC membrane
-Ag development depends on 3 independent inherited genes -H, Secretor gene, and the Lewis gene.
-Le gene -dominant and le -amorph with no enzyme being produced
-Antigens present on RBC are Lea or Leb
Le, H, and Se Genes
Le, H, and Se Gene = Lewis and Secretor
Le, H, and Se Gene = Lewis and Secretor
-when these genes are inherited varying amounts of precursor chains
converted depending on the ABO type (H antigens are increased in O individuals).
-H, A, B, Lea, and Leb substances can be found in secretions
-Most of the Lea is converted to Leb by the Se gene
-Red cell absorbs only Leb in significant amounts so there is none or a trace of Lea AG on RBC
Le, H, and se Genes
Le, H, and sese Gene = Lewis and Non-Secretor
Le, H, and sese Gene = Lewis and Non-Secretor
1) Only Lea produced
2) NO further addition of sugars
3) Red cell Membrane only absorbs Lea
4) Plasma contains only Lea soluble antigens
5) sese gene, NO H, A, B in soluble form
Lewis Genes
-only the LE gene
* NO Lea or Leb gene
* They are not alleles Lea or Leb
They are the AG found on the rbc
Only one antigen is absorbed onto the red cell membrane
Lewis Ag
-not fully developed at birth
-NB are usually Le(a-b-) and maybe typed as Le(a+b+) until the transition to Le(a-b+)
-phenotyping is unreliable until 6 years of age, because phenotyping is able to change because AG can be reabsorbed so it wouldnt be an prominent on the RBC membrane
Lewis Antibodies
-IgM AB with no significance
-wide temperature range
-not well developed at birth but can bind complement and cause hemolysis
-does not cause a transfusion reaction
-enhances effect on enzymes
* Possible for Le(a-b-) individuals to make Anti-Lea and Anti-Leb
* Anti-Leb is rare in Le(a+b-) individuals
* Le(a-b+) would NOT produce Anti-Lea
Major OBG Systems
Kell - Warm AB
Duffy - Warm AB
Kidd - Warm AB
MNSs
P - carb -Cold AB
Li - carb
Lewis - carb - cold AB
blood group system grouped according to similar antigens inherited by alleles at a single
gene locus or linked loci.
Antigens can be multi-pass proteins like (Rh), single-pass proteins with carbohydrates components or carbohydrate branches (ABO).
Ficin or
Papain
an antibody no longer reacts with the panel of red cells, after the red cells have been pretreated these enzymes
MNSs System
- on chromosome 4. due to proximity, they are inherited as a haplotype
-* M and N antigens are co-dominant alleles - S and s antigens are co-dominant alleles
-inherited like the Rh system and well developed at birth
- high phenotype frequency
-single pass glycoproteins
-integrated into the RBC membrane
-GYPA and GYPB genes encode for the MNS system
-* Glycophorin A (GPA) codes for M and N antigens
* Glycophorin B (GPB) codes for S and s antigen
* U antigen is always present when S or s is inherited.
Anti M
Antibody M
IgM
-cold reacting, depending on pH
-doesnt need RBC stimulation like ABO grouping
- can be IgG
-if it reacts at 37 with AHG and doesn’t disappear it is important
-rarely causes HDFN
-does show dosage so it reacts stronger with HOMO cells
-destroyed by enzyme-treated cells
