Blood Banking Flashcards
Identified as antigens capable of initiating an immune response, which can affect RBC compatibility
Surface markers
T/F: surface markers are identified as antigens capable of initiating an immune response, which can affect RBC compatibility
True
Antigens are either __ or __
Sugars
Proteins
T/F: antigens are either sugars or proteins
True
Blood group describe by Karl Landsteiner in 1900
ABO blood group
Who discovered ABO blood group
Karl Landsteiner
Year ABO blood group was discovered
1900
Most important blood group system
ABO blood group
Principle of ABO blood group
Individuals possess antibodies against antigens they lack
T/F: in ABO blood group, individuals possess antibodies against antigens they lack
True
Char of antibodies in ABO blood group (4)
Production initiated at birth, but titer low until 3-6 mos of age
If A or B Ag is absent, person will make antibodies against missing antigens
Naturally-occurring
Complementary relationship enables ABO testing of Px sera and RBCs
ABO antigens exhibit this kind of inheritance
Autosomal codominance
T/F: ABO Ags exhibit autosomal codominant inheritance
True
Location of ABO
Chromosome 9
ABO: One locus in chromosome 9 is occupied by one of 3 alleles: (3)
A, B, O
T/F: ABO: One locus in chromosome 9 is occupied by one of 3 alleles: A, B, O
True
T/F: ABO: Each person has a pair of chromosomes that carry one allele
True
Group O is a
Silent allele
Silent allele
Group O
Allele wherein gene product not detectable
Silent allele or amorph
Secretor genes: location
Chromosome 19
Secretor genes (2) -describe each
Hh- H antigen on RBC
Se- H antigen in secretions
T/F: Hh and Se are on chromosome 19 and are closely linked
True
T/F: H and Se genes: each locus has 2 recognized alleles, 1 allele is an amorph
True
Produces a glycosyltransferwse that acts on type 2 chains- H Ag on RBCs
H gene
H gene produces a glycosyltransferwse that acts on type __ chains- H Ag on RBCs
2
Produces a glycosyltransferwse that acts on type 2 chains- H Ag on __
RBCS
T/F: H gene produces a glycosyltransferwse that acts on type 2 chains- H Ag on RBCs
True
Non-secretors (3)
h gene
se gene
Produces a glycosyltransferwse that acts on type 1 chains- H Ag in secretions
Se gene
Se gene produces a glycosyltransferase that acts on type __ chains- H Ag in __
1, secretions
Bombay phenotype
Genotype hh
Genotype hh
Bombay phenotype
Very rare, doesn’t make transferase to form H Ag
Genotype hh or Bombay phenotype
T/F: hh is very rare, doesn’t make transferase to form H Ag
True
Char of Bombay phenotype (3)
Bombay RBCs fail to react with anti-A, anti-B, or anti-H lectin
Only blood from other Bombay phenotype scan be transfused
Bombay serum contains anti-A, anti-B, anti-A,B, and anti-H (potent, reacts strongly at 37。C
Genotype hh Se
Para-Bombay phenotype
Normal amount of H ag is detectable in saliva because these are secretors but may produce a weak anti-H
Para-Bombay phenotype
T/F: para-Bombay phenotype: Normal amount of H ag is detectable in saliva because these are secretors but may produce a weak anti-H
True
A subgroups:
__% A1
__% A2 or weaker
80%
20%
Inheritance of A2 gene:
Small amount of H Ag conversion
T/F: Inheritance of A2 gene: Small amount of H Ag conversion
True
T/F: A subgroups have same immunodominant sugars
True
Differentiation of A1 and A2 subgroups based on:
Reactivity with anti-A1 (lectin [Dolichos biflorus] or human-based)
-A1 cells react with anti-A1 while A2 cells don’t
T/F: Genes at 3 separate loci control the presence and location of the A, B, and H antigens: ABO, Hh, and Se
True
H gene
Gene product/enz:
Antigen:
Immunodominant sugar:
H gene
Gene product: L-fucosylytransferase
Antigen: H antigen
Immunodominant sugar: L-fucose
A gene
Gene product/enz:
Antigen:
Immunodominant sugar:
A gene
Gene product: N-acetylgalactosaminyltransferase
Antigen: A antigen
Immunodominant sugar: N-acetylgalactosamine
B gene
Gene product/enz:
Antigen:
Immunodominant sugar:
B gene
Gene product: D-galatosyltransferase
Antigen: B antigen
Immunodominant sugar: D-galactose
Generally, A and B genes encode these that produce A and B antigens
Glycosyltransferases
T/F: genes do not directly encode for the antigen but encode for the ENZYME that transfers the immuno dominant sugar that confers the specificity
True
T/F: O gene does not encode a functional enzyme because it is an amorph gene
True
T/F: A and B genes are dominant genes while O gene is an amorph gene
True
T/F: weak a subgroups show weaker reactivity than A2
True
Weak A subgroups (2)
A3
Ax
Weak A subgroup with mixed-field pattern of agglutination with anti-A
A3
Weak A subgroups make up __% of the population
1%
T/F: weak A subgroups make up 1% of the population
True
Weak A subgroup with stronger reaction with anti-A, B than anti-A
Ax
Weaker A subgroups are detected by
Elution and adsorption of anti-A
Very rare, little consistency in description, recognized by variations in strength of reaction with anti-B and anti-A,B
B subgroups
People typed as A and B generally produce this class of antibodies and small quantities of this class of antibodies
IgM class ABO antibodies *and small quantities of IgG
People typed as O produce this class of antibodies
IgG class antibodies- anti-A,B
Readily crosses the placenta
IgG
Aka RBC typing
Forward typing
Aka forward typing
RBC typing
Reagents for forward typing (2)
Anti-A and anti-B
Anti-A and anti-B used for forward typing are generally __ this designed to give at least __ or stronger reactions
Monoclonal antibodies
3+
aka serum typing
Reverse typing
Aka reverse typing
Serum typing
ABO testing which uses anti-A and anti-B
Forward typing
ABO testing which uses A1 cells and B cells
Reverse typing
Reagents used for reverse typing
A1 cells and B cells
Reagent cells for ABO typing are Rh _
Rh negative
T/F: reagent cells for ABO typing are Rh neg
True
RBCs contain __ or __ on their __ or as __
RBCs contain surface markers or antigens on their surface or as part of their membranes
Expected reaction in reverse typing
-anything weaker may indicate __
2+
Serum problem
T/F: expected result in reverse typing is 2+ and anything weaker may indicate serum problem
True
Forward and reverse typing are both required in patients and donors to serve as __ for each other
Check
T/F: Forward and reverse typing are both required in patients and donors to serve as check for each other
True
Non-routine reagents (3)
-and use/s or description of each
Anti-A,B -used to aid in classification of subgroups -confirm group O units (retype) A2 cells -discrepancy resolution Lectins a. Anti-A1: Dolichos biflorus b. Anti-A2: Ulex europaeus
Uses of anti-A,B (2)
- used to aid in classification of subgroups
- confirm group O units (retype)
Process of confirming group O units
Retype
Use of A2 cells
For discrepancy resolution
Lectins (2)
-also describe
Anti-A1 from Dolichos biflorus
Anti-H from Ulex europaeus
Source of anti-A1 and anti-H
Anti-A1 from Dolichos biflorus
Anti-H from Ulex europaeus
Dolichos biflorus as source of this lectin
Anti-A1
Ulex europaeus as source of this lectin
Anti-H
Causes of ABO discrepancies: 4 groups
Weak or missing antigen reactivity
Extra antigen reactivity
Weak or missing antibody reactivity
Extra antibody reactivity
Weak or missing antigen reactivity (6)
-describe each
Mixed cell populations and chimeras -review transfusion and transplant history Excessive blood group substance -can neutralize reagents Newborns -lower number of A a/o B antigen sites Subgroups of A and B -A3, Ax, Ael -B subgroups rare Leukemia -weak expression of A a/o B antigen Cis-AB phenotype -rare chromosome
MOST common cause of chimerism
Transfusions
T-F: transfusions are the most common cause of chimerism
True
Extra antigen reactivity (4)
DAT +
Acquired B
Contaminated cord blood samples
Unwashed cell suspensions
Patient types as AB, but serum contains anti-B
Acquired B
Transient condition associated with disorders of the gastrointestinal tract
Acquired B
Acquired B is a transient condition associated with disorders of the ___
Gastrointestinal tract
T/F: acquired B is a transient condition associated with disorders of the gastrointestinal tract
True
T/F: certain clones used to make monoclonal anti-B cause strong reactions with acquired B cells
True
T/F: Acquired B: strength of reactivity is weakened with reduced reagent pH
True
Strength of reactivity is weakened with reduced reagent pH
Acquired B
Strength of reactivity is weakened with __ reagent pH
Reduced
Associated with colonic bacterial infections
Acquired B
Test RBCs with human anti-B acidified to pH __
6.0
T/F: strongly reactive DAT cells can spontaneously agglutinate with cell grouping reagents
True
Most often seen with Rh typing reagents
Direct antiglobulin test +
T/F: DAT + can occur with ABO reagents if coating antibody is cold-reactive
True
Can occur with ABO reagents if coating antibody is cold-reactive
DAT +
DAT + can occur with ABO reagents if coating antibody is __
Cold-reactive
Resolution for DAT + (3)
Wash cells with 37•C
Incubate Px cell suspension at 37•C and wash with warm saline
Elute antibodies from RBCs with chloroquine diphosphate or dithiothreitol (DTT)
Used to elute antibodies from RBCs to resolve DAT + (2)
chloroquine diphosphate or dithiothreitol (DTT)
Main cause of contaminated cord blood samples
Wharton’s jelly
How to resolve contaminated cord blood samples (2)
Wash w/ saline 3 or 4x, retest
Request heel-stick sample
Sample requested to resolve contaminated cord blood samples
Heel-stick sample
Washing can dissipate problems caused by (2)
Px antibodies to reagent components
Rouleaux formation
Resolves Px antibodies to reagent components and rouleaux formation
Washing
Weak or missing antibody reactivity (4)
-describe also
Chimeras -persistent chimeras develop a tolerance to both cell populations Missing antibodies -immunocompromised Px Low antibody levels -newborns and older Px Subgroups -cells from A subgroup Px's often typed as group O
T/F: persistent chimeras develop a tolerance to both cell populations
True
Low antibody levels usually seen in (2)
Newborns
Older pop
Missing antibodies are usually in
Immunocompromised Px’s
Cels from A subgroup Px’s often typed as group __
O
T/F: titer of anti-A is usually higher than that of anti-B in most group O
True
T/F: subgroups may be due to anti-A1 or other allo antibodies and not by anti-A
True
Testing panel of (3) can help determine of subgroup discrepancy exists
A1, A2, and O cells
Rouleaux formation: resolution:
Saline replacement technique
How to resolve cold-reactive antibodies (allo antibody or autoantibody) (2)
Use of mini-cold panel
Testing with A2, O, and autologous cells, in addition to tests with A- and B cells
How to resolve passively acquired antibodies (1)
Check Px transfusion history
Extra antibody reactivity (3)
Cold-reactive antibodies (autoantibody or alloantibody)
Passively acquired antibodies
Rouleaux
Suggested resolution process for ABO serologic problems (5)
Repeat testing on same sample
Wash Px cells
Obtain Px info
-diagnosis
-historical blood group
-history: transfusions, transplants, medications
Review results with group O RBCs and autocontrol
Obtain new sample if contamination suspected