Unit 4: Other Blood Groups Flashcards
How is Lewis blood group system unique?
Lewis blood group system gets adsorbed onto the RBC membrane from plasma
Where are the lewis antigen located?
type 1 glycosphingolipids
Why are Lea and Leb not antithetical?
they don’t result from alternative alleles of a single gene
What is fucosyltransferase?
an enzyme that transfers a l-fuc sugar from GDP-fuc donor substrate to an acceptor
What produces lewis antigens?
tissue cells (plasma/body secretions)
Where is the Se gene located?
chromosome 19
What are the two genes of Se?
Se and se (absence)
Where does the Se gene add L-fuc?
to type 1 precursor chains (body fluids)
What do you require to have Lewis B?
a Secretor
In Le(a+b-) what genes are present? What is secreted?
Le and H genes, Le(a) antigen substance secreted
In Le(a-b+) what genes are present? What is secreted?
Le, H and Se genes, A, B, H, Le(b) and small amts of Le(a)
In Le(a-b-) what genes are present? What is secreted?
nothing, possibly have Se (must test)
If you have a weak secretor gene what occurs?
you will have more Le(a) because it makes less Le(b) and causes Le(a+b+)
Cord blood and RBCs of newborns type as Le___
Le(a-b-)
In newborn secretions, if they have Le gene, what do they have?
Le(a) in secretions (saliva)
At how many days old will Le be present on RBCs? What will show?
10 days, Le(a+b-)
After 10 days… what will newborns type as
Le(a+b+)
Why does Lw blood group substance transfusion rarely cause hemolysis of RBCs?
they bind to free-floating anti-Le(a or b) in plasma rather than ones attached to RBC membrane
What does Anti-Le(bH) react with?
group O Le(b+) and A2 Le(b+)
In the serum of Le(a-b-) secretors, what is found?
Anti-Le(a) and Anti-Le(b)
What are techniques to ID anti-Le’s?
neutralization of antibodies
enzyme-treated cells that enhance reactivity
Why don’t individuals who type Le(a-b+) make anti-Le(a)?
because they still have small amounts of Le(a)
Lewis system is known to be associated with…
peptic ulcers ischemic heart disease cancer kidney transplant rejection helicobacter pylori
Where are antigens M and N found?
glycophorin A
Where are the S antigens found?
Glycophorin B
What antibody is found frequently in human sera and agglutinates in saline?
Anti-M
Anti-M exhibits the _______ with the N antigen
dosage effect
Anti-M fails to react with….
enzyme-treated red cells (it gets destroyed)
What are not common antibodies that are usually IgG and immune in nature?
Anti-S and Anti-s
What antibody is rare and reacts with the cells of most people?
Anti-U
What phenotype produces Anti-U? Which population is it almost exclusively found?
S-s-U-
African American
En(a-) phenotype results from…
gene deletion at GYA locus for glycophorin A
What is the M(k) phenotype?
single near-complete deletion of both GYPA and GYPB so they will have no M, N or S
Which enzyme(s) destroys only S & s?
chymotrypsin
Which enzyme(s) destroys only M & N?
trypsin
ZZAP
DTT w/ papain or ficin
AET
Which enzymes destroys all MNS?
ficin
papain
bromelin
pronase
Where are P & Globoside blood groups found?
RBCs, lymphocytes, granulocytes and monocytes
What is the common precursor for globoside?
lactosylceramide
What are the antigens for the P & Glb blood group system?
P
P1
P(k)
Luke (LKE)
What antigen is assigned to the Glb system?
P antigen
How long could it take for P1PK to be fully expressed?
7 years
What could inhibit the P1 antigen expression?
In(lu) gene
Where is the P1 antigen found?
in individuals with a hydatid cyst infection
Where does the P1 gene reside? Where does the P antigen (GLOB) reside ?
chromosome 22
chromosome 3
What is known as the Donath-Landsteiner antibody?
(IgG) Anti-P
Describe why Anti-P is a powerful biphasic hemolysin…
it attaches to red cells in the cold buy lyses them in warmer temps
What are the diseases associated with the P1Pk and Glb blood group systems?
hydatid cyst infection fascioliasis adenocarcinoma HTRs HDNs PCH Tertiary syphilis acute condition secondary to viral infection shigella dysentery E. coli-associated hemolytic uremic syndrome UTIs
What is the structure of i vs I?
i is linear and I is branched
How are i and I antigens formed?
glycosyl transferases
What is the principle of adsorption?
removes antibodies from serum by adding target antigen, it gets agglutinated and then removed by centrifugation
What is human plt concentrates used for?
to adsorb Bg-like antibodies from serum
What is RESt? What does it process?
ID’s cold-reacting autoantibodies, it processes I, H and IH-like structures
How are autoantibodies removed?
adsorption techniques
If reactivity occurs during autoadsorption…
autoantibody remains in serum and further adsorption is necessary
Describe homologous adsorption…
patient is phenotyped, then phenotypically matched RBCs are used for the adsorption in place of autologous cells.
What blood group systems are treated with enzymes to be negative for DAT?
duffy and MNS
What is the most critical step in preparing the eluate?
original washing
What are the enzymes used to separate specificities and allows for ID?
trypsin
ficin
bromelin
What do enzymes remove on the RBC surface?
Sialic Acid residues or glycoproteins
Enzymes may be used in place of which enhancement medias?
LISS/PEG
What is the purpose of pretransfusion testing?
to reveal any possible incompatibility between a donor’s blood and the recipient’s blood
What is the second purpose of pretransfusion testing?
to select blood products with acceptable survival rates
What is the major cause of transfusion-associated fatalities?
clerical errors
What percentage of the errors are misidentification?
47%
What is the preferred specimen for transfusion services?
plasma (no waiting time to clot)
What is the preferred specimen for complement ID since EDTA could neutralize complement?
serum
What is the major difference between a T/S vs a T/C?
in a T/C, the donor RBC is mixed with recipient RBC
What occurs in a T/S and T/C if you have a positive antibody screen?
identify the antibody, perform AHG Xmatch then set aside antigen-negative blood for patient
What is the most common bacterial contaminant?
Yersinia enterocolitica
What are the phases of cross-matching?
Immediate spin crossmatch
antiglobulin crossmatch
Weak D (once)
What test is sufficient for a patient receiving large volumes of plasma?
immediate spin crossmatch
What are the massive transfusion measurements?
8-10 RBC units/24 hours or 4-5 RBC units/1 hour
How can complete coagulation be accelerated?
adding thrombin
What is the purpose of the MSBOS?
to promote more efficient utilization of blood and establish realistic blood ordering levels
What is required for issuance of blood/blood components?
After all pretransfusion testing
after all serological discrepancies resolved
a minimum of 2 patient identifiers
a written request
