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Medical Laboratory Review: Immunohematology
Terms in this set (321)
What is immunogenicity?
it is a term used to describe the ability of an antigen to stimulate the production of its corresponding antibody in a person that lacks the antigen
Chemical structure of the antigen (factor of immune response)
Antigens which are primarily oligosaccharides tend to stimulate IgM, while antigens that are protein based produce IgG. Whether the antigen is more exposed or buried in the membrane also influences the degree of response.
The degree of foreigness (factor of immune response)
If an antigen is similar to what the body makes, it may not have a large reaction
The number of red cells introduced and the amount of antigen they carry (factor of immune response)
A small number of red cells can cause immunization, but the risk increases as the quantity increases. In fact, the significance may be more pronounced on the opposite end of the scale-a large infusion may paralyze the immune response.
The route of introduction (factor of immune response)
Response varies whether it is given intramuscularly, subcutaneously, etc.
antibody production in response to the first exposure to a foreign immunogen. Two to six months before the antibody is detectable. Usually IgM.
a second exposure to the same immunogen will result in production of antibody and may be detectable in a few hours, days, or a few weeks. Sometimes called the anamnestic response. Usually IgG.
Antibody produced in response to non-erythrocyte immunogens. The source of the antigen is natural and typically makes a primary response (IgM).
Antibody-like materials in nature that react specifically with blood group antigens. Used in the investigations of unusual blood types because of their precise specificity.
Most blood group antibodies fall into which two immunoglobulin classes?
IgM and IgG
____ binds to antigens
___ site of complement fixation, placental transport, and reaction with anti-human serum
The region of the IgG antibody where the antibody can open or bend is called the
The structure of an IgM molecule consists of ____ subunits?
The specificity of an antibody for its corresponding antigen depends on
conformational fit and the number of unlike charge pairs
Cold antibodies with usually react only below ___ degrees centigrade
Antigen-antibody reactions proceed more ____ in low ionic strength solutions than in normal saline
Red blood cells which simply have antibodies attached to them (without visible changes) are called _______ cells
Cells which have been sensitized by incomplete anitbodies can be agglutinated in vitro using ______ which contains antibodies to human gamma globulins
When antigen-antibody reactions lead to red blood cell lysis, the lysis is mediated by the
Anti-human serum specific for complement is produced by injecting rabbits with purified human....
Any test which incorporates anti-human serum is called an
Direct Coombs test
anti-human serum is added to agglutinate the patient"s sensitized cells
Indirect Coombs test
Reagent cells are added to be sensitized by antibodies in the patient's serum.
If unattached globulins are not removed during the washing phase of the antiglobulin test, a false ___ test may result
Agglutination of RBCs requires anti-human serum of altering the suspending medium
Agglutination of RBCs proceeds without adding anti-human serum
The surface of a RBC has a strong net _____ charge
The surface charge is maintained by the large number of
sialic acid residues attached to the membrane
The minimum distance between two RBCs is influenced by the _____ potential
By raising the dielectric constant of the medium, the zeta potential is
Antibodies which bind to red cells _____ the water of hydration of the cells
Proteolytic enzymes such as trypsin decrease the net negative charge of a red cell by
cleaving negative charges from the cell's surface
These antibodies are more reactive with enzyme-treated red cells
These antigens are lost when cells are treated with proteolytic enzymes
M and N
Breaks polypeptide bonds
releases sialic acid
The antigenic determinants of the ABO,P Lewis, and MN systems are
Enzymes which assemble sugars into oligosaccharide chains are called
The ABO locus is on chromosome....
The antigenic determinant of an A, B or H antigen is the
Terminal cugar of the oligosaccharide chain and the few adjacent sugars
L-fucose is the antigenic determinant to the
D-galactose is the antigenic determinant to the
Type I and type II chains differ in
the carbon to carbon linage between their terminal and subterminal sugars
Type I precursor chain is found in
Type II precursor chain is
an integral part of the red cell membrane
Which ABO group reacts most strongly with anti-H?
H gene produces the
has no gene product detectable
A and B antigens (are/are not) synthesized in the rare h/h individual
Homozygous h/h individuals appear to be group
Phenotypic names for h/h are
Bombay, O sub h, ABH sub null
A1 and A2 differ in
the efficiency with which their transferases convert H chains to A chains.
The Se and se genes control the secretion of A,B and H
substances in body fluids
P1 antigens are made of
Like A and B antigens, P1 antigens are synthesized by
P1 antigens and H antigens are synthesized from (same or different) precursor chain
The type II precursor chain in the ABO system is the same structure as
paragloboside in the P system
The P1 antigen is formed by the addition of
The P1 antigen is not synthesized when its transferase is absent and the resulting phenotype is called
When the antigens P1, P,Pk are absent the phenotype is called
pp or Tj(a-)
How do Lewis antigens get on the red cell?
They are absorbed from the plasma
Lewis antigens are made from
Lewis antigens are constructed by enzymes called
Some transferases can use more than one ...
The addition of a new sugar to a substrate may produce a new
in the Lewis blood group, transferases can produce antigen only if the proper
substrate has been performed
Is the Le gene present in Le(a+b-)?
is the Le gene present in Le(a-b+)?
Is the Se gene present in Le(a+b-)?
Is the Se gene present in Le(a-b+)?
One fucose molecule added to the type 1 precursor chain
One fucose molecule added to the type 1 H chain
A and B transferases of the ABO system will add sugars to which Lewis substances?
The Se gene controls the production of a fucosyl transferase which adds fucose to the
Type I precursor chain
Which gene controls the production of a fucosyl transferase which adds fucose to a type II precursor chain?
h/h and se/se produce what phenotype?
h/h and Se/se or h/h and Se/Se produce what phenotype?
What structures carry MNS and s antigens?
Glycoproteins (they are composed of polypeptide chains to which sugars have been added) The more correct term would be sialoglycoprotein (SGP) because a majority of the sugars are sialic acid.
The antigens of the MNSs blood group are
Which glycophorin would you find the antigenic determinants S and s on?
Which glycophorin would you find the antigenic determinants M and N on?
Depending upon whether the blood group is M or N, glycophorin A differs in the _____ amino acids of the external segment
first and fifth
The terminal amino acid segment of glycophorin B is the same as that of glycophorin A when the blood group is
The configuration of the oligosaccharides in the MNSs system is controlled by the
sequence of the amino acid residues
The loci for M and N and for S and s are (think linkage)
The molecular structures of the Rh antigens are understood in _____ detail.
All the facts currently known about the Rh system can be accounted for by which theory
The Fisher-Race theory involves....
three pairs of genes
The Wiener theory involves
one pair of genes
For the D locus, what are the possible alleles for Fisher-Race?
For the C locus, what are the possible alleles for Fisher-Race?
For the E locus, what are the possible alleles for Fisher-Race?
In the Fisher-Race theory, which allele is thought to be a silent gene?
According to the Fisher-Race theory, which antigens could be determined in the laboratory in a person whose genotype was DCe/dCE?
In the Wiener theory, ----- major alleles are postulated as possible occupants of the Rh locus.
According to the Wiener theory, each allele controls the synthesis of a structure on the red cell membrane called an ------ which can be identified by its parts or ------ that react with specific anitbodies.
In contrast, to the Fisher_race and the Wiener nomenclature, The Rosenfield nomenclature is based on ?
Antisera test results
The terms "Rh positive" and "Rh negative" refer to the presence or the absence of the antigen
D or its variant D^u
If a woman is Rh negative and her husband is heterozygous for D, then the probability that a child of theirs will inherit D is
Postulating a genotype in the Rh system is done by
Statistical methods based on testing with antisera to D,C,c,E, and e antigens
Rh genotypes are considered "presumptive" or "most probable" because there are alternative choices in
almost every instance
The frequency of Rh genotypes ______ in different racial groups
The antigenic determinants of the Rh system are now believed to be _________________ embedded in the red cell membrane
part of a single unit
The antigenic determinant of the D antigen is probably a relatively _____ portion of the protein carrying the Rh antigens
A set of contiguous genes inherited as a unit is called a ____
Small changes in the amino acid sequence may give rise to_______ on the red cell surface
Weakly reactive D positive cells are designated
The D antigen is thought to be made up of many antigenic determinants called
Anti-D specific for one epitope could be produced by a person missing an epitope if the person were exposed to
common D positive red cells
The C gene in ____ position my suppress the expression of D on red cells
Hereditary D^u has a _______ of normal antigens
____ suppresses the Rh genes by independently inherited genes
____ is an abnormally structured D antigen
Suppression of a D gene by a C gene in trans position is caused by
gene interaction D^u
A minus-minus phenotype may be the result of a
Such a minus-minus phenotype is called a
recessive minus-minus phenotype
A minus-minus phenotype may also be the result of a modifier gene which suppresses the action of
structural blood group genes
Which type of gene can affect more than one blood group system?
a ---/--- is caused by
a homozygous amorph
X^0r is caused by
a modifier gene
In the Kell system, X^k is a
In the Kell system, K^0 is a
In the Duffy system, the amorphic gene is labeled
A minus-minus phenotype in the Kidd system appears to be caused by a
In the Lutheran system, ln(Lu) is a
In the Lutheran system, Lu is a
Multiple paired allelic genes which are closely linked are called a gene complex or gene ______
When a modifier gene suppresses the expression of a blood group, it suppresses
all of the genes in one cluster
When the amorph K^0 (or Lu) is present as a heterozygote ___________ fails to make antigen
only one gene cluster
The Xg^a antigen is known to be controlled by a gene on the ____ chromosome
Which blood group is most important in blood transfusion?
What are two reasons why ABO grouping is so important
Anti-A and or anti-B are present in serum of almost every person and ABO antibodies fix complement and can cause intravascular hemolysis
An error in ABO grouping (can/cannot) be fatal in a tranfusion setting
The crossmatch affords an additional measure of
Name two tests required to determine an individuals ABO group
red cell grouping and reverse grouping
The origin of ABO antibodies present in a one-month-old infant is the ____ immune system
Blood grouping sera anti-A and anti-B used in ABO grouping contain
The A and B antigens are present in very ______ numbers on red cells
In ABO grouping, the reaction is
fast, requiring no incubation
When a discrepancy arises between a patient's red cell group and the reverse group...
additional test must be performed to clarify the discrepancy
In the ABO grouping, reagent controls can be part of _________ or may be set up _________
The test system, separately
Controls on the method and conditions used in a test system are called
When testing group A, B, or AB red cells with Blood Grouping Sera Anti-A and Anti-B, _________ reactions are expected
Weak reactions in red cell grouping a healthy person may indicate _____
A subgroup of A or B
When testing the cells of donors, the danger is that subgroups of A or B may be mistyped and labeled group _____
Which are more common, subgroups of A or B?
The majority of Caucasians inheriting an A gene produce a normal A antigen called
A sub 1
True or false: The A sub 1 transferase is produced in a greater amount than the A sub 2 transferase.
True or False: The A sub 1 transferase is more efficient than the A sub 2 transferase
Group A sub 1 cells react weakly with _____ sera
Group A sub 2 cells react intermediately with ______ sera
Group O cells react strongly with ________ sera
People with A sub 2 or A2B cells may produce anti-_____
A sub 1
Extracts of seeds which agglutinate human red cells with high degree of specificity are called
Red cells which react weakly or not at all with human anti-A sub 1 serum but which are agglutinated by anti-A sub 1 lectin are called
Patients who have been transfused with blood of an ABO group other than their own ABO group may show ______________ agglutination
Chimeras most often arise from
exchange of primordial blood cells between non-identical twins early in fetal life
Mixed-field agglutination is _________ seen when testing subgroup A sub 3 with anti-A
In leukemia, A and or B antigens may become progressively _______ but revert to normal during remission
bacterial enzymes may cause group A people to acquire ______________
altered antigens very similar to B antigens
T or Tk receptors on red cells may be exposed by
Anti-T and anti-Tk are Ig__
The Cad positive trait is
inherited, not acquired
The antibody which reacts with Cad positive cells has the same specificity as ____________
The mixed-field agglutination seen when testing Tn-activiated red cells with anti-A and anti-B is due to their reaction with
In leukemia or hypogammaglobulinemia, the patient's ABO antibody levels would be expected to
Levels of Anti-A and Anti-B ______ expected to vary depending upon patients age
When a patient's serum reacts with A sub 1 and B cells but hid or her red cells do not appear to be type O, the reaction is most likely do to ____
The major antigen of the Rh-hr system is the D antigen, which also is called the ____________ antigen
Rh sub o
D antigen or D^u present of the red cell is Rh _______
neither D nor D^u is present on the red cell membranes
An Rh negative person would normally ______________ to have anti-D in his serum
not be expected
The D antigen is a ______________ immunogen
Natural substances chemically similar to the D antigen _________ been found
What are the two ways in which an Rh neg person can be exposed to D antigen
Transfusion with Rh positive blood
Passage of Rh positive fetal cells to an Rh negative mother
Rh negative patients (are or aren't) commonly transfused with Rh positive blood
Fetal-maternal passage of red cells usually occurs
in the third trimester and especially at delivery
The number of women immunized to D by fetal-maternal passage of red cells has ________ over time
Immunization by Rh positive cells at delivery is suppressed by
postpartum administration of Rh immune globulin (RhoGam)
Rh immunization due to fetal-maternal passage of cells as a result of trauma during pregnancy can be suppressed by
Antepartum administration of Rh immune globulin
If an Rh negative person is accidentally transfused with Rh positive blood, immunization can be suppressed by
administration of an adequate dose Rh immune globulin
Granulocyte transfusions should be both ABO and Rh compatible because
Large numbers of red cells are introduced with the granulocytes
Platelet preparations (are/are not) entirely free of red cells
In an Rh negative person who has already been Rh immunized, transfusion with Rh positive cells may lead to
a severe or fatal transfusion reaction
The presence or absence of the D antigen is demonstrated by testing red cells with
Anti-D (Anti-Rh sub o)
Red cells are not agglutinated by anti-D may be further tested for what variant of D?
Other antigens of the Rh system (are/are not) routinely tested for
False positive agglutination of sensitized red cells is more likely to occur with an antiserum prepared in a ______ diluent
The antibodies in blood grouping serum anti-D for saline tube test are
chemically modified IgG antibodies in which the disulfide bonds of the hinge region are broken agglutinate red cells without the aid of
high concentrations of albumin or synthetic porentiators
Which type of antibody is used in making blood grouping serum anti-D novasera for saline tube and slide tests
chemically modified IgG
Rh immunization due to fetal-maternal passage of cells as a result of trauma during pregnancy can be suppressed by
Cells which are of the D^u phenotype ______ stimulate the production of anti-D
Cells which are not agglutinated by anti-D but also absorb the antibody and are detected in the antiglobulin procedure are called
The D^u status of a pregnant woman who has been typed as D neg should be established
early in pregnancy
Variant forms of C, c, E, and e antigens ________ been found
What problem in Rh typing may be caused by variant forms of Rh antigens?
Unusually weak agglutination
What problems in Rh typing may be caused by using a high-protein potentiated Rh antiserum?
False pos, sticky buttons
a PATIENT WHOSE RED CELLS TYPE AS d NEG, BUT ARE AGGLUTINATED IN THE TEST FOR d^U AND WHO HAS A POSITIVE DIREST ANTIGLOBULIN TEST SHOULD RECEIVE
d NEG BLOOD
Donor red cells which type as D neg but are agglutinated in the test for D^u and exhibit a positive direct antiglobulin test _______________ be used for transfusion
Antibodies found in the absence of the corresponding antigen are called
A positive direct antiglobulin test denotes the presence of
antibody on red cells
Autoantibodies indicate ______________
A positive direct antiglobulin test due to alloantibodies may be found in __________________ and _______________
transfusion reactions, hemolytic disease of the newborn
What test is recommended for any patient about to receive blood transfusions?
antibody screen and crossmatch
Antibody that usually agglutinates red cells in saline
Antibody may sensitize red cells in saline, albumin, or low ionic strength solution
In hemolytic disease of the newborn the extent of red cell destruction depends on the presence of the antigen on the fetal cells and on the _____________ of the antibody
titer or level
In prenatal screening, complement is ____ important than in a transfusion situation
In which situation should amniotic fluid be monitored?
When the antibody is one that is known to cause HDN and the titer is 16 or greater
Donor antibodies should be identified to avoid
the confusion that passively infused antibodies can cause
What type of serological testing does the blood bank technologist perform when determining the blood group of a patient?
If anti-K reacts 3+ with a donor cell with a genotype KK and 2+ with a Kk cell, the antibody is demonstrating:
Carla expresses the blood group antigens FyA, FyB, and XgA. James shoes expressions of none of these antigens. What factor may account for the absence of these antigens in James?
Which of the following statements is true?
An individual with the BB genotype is homozygous for B antigen
Which genotype will give rise to the Bombay phenotype?
Meiosis in cell division is limited to the ova and sperm producing four gametes containing what complement of DNA?
A cell that is not actively dividing is said to be in :
Which of the following describes the expression of most blood group antigens?
What blood type is not possible for an offspring of AO and BO mating?
All are possible
The alleged father of a child in a disputed case of paternity is blood group AB. The mother and child are group O. What type of exclusion is this?
If the frequency of gene Y is 0.4 and the frequency of gene Z is 0.5, one would expect that they should occur together 0.2 (20%) of the time. In actuality, they are found together 32% of the time. This is an example of:
In the Hardy-Weinberg formula, p2 represents...
The homozygous population of one allele
In this type of inheritance, the father carries the trait on his X chromosome. The has no sons with the trait because he passed his y chromosome to them; however, all his daughters will express the trait.
Why do IgM antibodies, such as those formed against the ABO antigens, have the ability to directly agglutinate red blood cells and cause visible agglutination?
IgM antibodies are larger molecule and have the ability to bind more antigen
Which of the following enhancement mediums decreases the zeta potential, allowing antibody and antigen to come closer together?
This type of antibody response is analogous to an anamnestic antibody reaction.
Which antibodies to a component of complement are contained in the rabbit polyspecific antihuman globulin reagent for detection of in vitro sensitization?
Anit-IgG and anti-C3d
Which distinguishes A1 from A@ blood groups?
An A2 person may form anti-A1; and A1 person will not for anti-A1
A patient's serum is incompatible with O cells. The patient RBCs give a negative reaction to anti-H lectin. What is the most likely cause of these results?
The patient may be a Bombay
What antibodies are formed by a Bombay individual?
Anti-A, B, and H
Acquired B antigens have been found in
Group A persons
Blood is crossmatched on an A pos person with a negative antibody screen, The patient received a transfusion of A positive RBCs 3 years agao. The donors chosen for crossmatch were A positive. The crossmatch was run on the Ortho Provue and yielded 3+ incompatibility. How can these results be explained?
The patient has an A2 with anti A1
A patient's red cells forward as group O, serum agglutinates B cells (4+) only. Your next step would be:
Incubate washed red cells with anti-A1 and anti-A, B for 30 minutes at RT
Which typing results are most likely to occur when a patient has an acquired B antigen?
Anti-A 4+, anti-B 1+, A1 cells neg, B cells 4+
Which blood group has the least amount of H antigen?
What type RBCs can be transfused to an A2 person with anti-A1
A or O
What should be done if all forward and reverse ABO results as well as the autocontrol are positive?
Wash the cells with warm saline, autoadsorb the serum at 4 degrees C
What should be done if all forward and reverse ABO results are negative?
Incubate at 22 degrees or 4 degrees to enhance weak expression
N-acetyl-D-galactosamine is the immunodominant carbohydrate that reacts with
A stem cell transplant patient was retyped when she was transferred from another hospital. What is the most likely cause of the following results? Anti-A neg, Anti-B 4+, A1 cells neg, B cells, neg.
What reaction would be the same for an A1 and an A2 person?
Positive reaction with anti-A,B
A female patient at 28 weeks gestation yields the following results: Anti-A 3+, Anti-B 4+, A1 cells neg, B cells 1+, O cells 1_
Alloantibody in patient serum
Which condition would most likely be responsible for the following typing results: Anti-A neg, Anti-B neg, A1 cells neg, B cells 4+
Weak or excessive antigens
Which of the following results is most likely discrepant?
Negative A1 cells
A 61 year old male with a history of multiple myeloma had a stem cell transplant 3 years ago. The donor was O pos and the recipient was B pos. He is admitted to a community hospital for fatigue and nausea. Typing results reveal the following: Anti-A 0, Anti-B 0, Anti-AB 0, Anti D 4+, A1 cells 4+, B cells 0
A complete Rh typing for antigens, C, c, D, E and e revealed negative results for C, D, and E. How is the individual designated?
Hos is an individual with genotype Dce/dce classified?
If a patient has a positive DAT, should you perform a weak D test on the cells?
No, the cells are already coated with antibody
Which donor unit is selected for a recipient with anti-c?
Which genotype usually shows the strongest reaction with anti-D?
Why is testing for Rh antigens and antibodies different than ABO testing?
ABO reactions are primarily due to IgM antibodies and usually occur at room temperature; Rh antibodies are IgG and agglutination usually requires a 37 degree incubation and enhancement media
Testing reveals a weak D that reacts 1+ after indirect antiglobulin testing. How is this result classified?
What is one possible genotype for a patient who develops anti-C antibody?
A patient developed a combination of Rh antibodies: anti-C, anti-E, and anti D. Can compatible blood be found for this patient?
rr blood could be used without causing a problem
A patient tests positive for weak D, but also appears to have anti-D in his serum, What may be the problem?
A D mosaic may make antibodies to missing antigen parts
Which offspring is not possible from a mother who is R1R2 and a father who is R1r?
Why is testing a pregnant woman for weak D not required?
An Rh-positive fetus may yield false positive results in a fetal maternal bleed.
What antibodies could an R1R1 make if exposed to R2R2 blood?
Anti-E and anti-c
What does the genotype -/- represent?
What techniques are necessary for weak D testing?
37 degree incubation and IAT
A patient types as AB and appears to be Rh positive on slide typing. What additional tests should be performed for the tube typing?
Rh negative control
According to the Wiener nomenclature:
There are multiple alleles at a single complex locus that determine each Rh antigen
A physician orders 2 units of leukocytes-reduced red blood cells. The patient is a 55 year old male with anemia. he types as AB neg, and his antibody screen in negative. There is only 1 unit of AB neg in inventory. What is the nest blood type that should be given?
Which technology may report an Rh-weak D positive as Rh neg?
A patient has the Lewis phenotype Le(a-b-). An antibody panel reveals the presence of anti-Le^a. Another patient with the phenotype Le(a-b-) has a positive antibody screen; however, a panel reveals no conclusive antibody. Should anti-Le^a be considered a possibility for the patient?
Anti-Le^a is not likely because even Le^b individuals secrete some Le^a
A tech is having great difficulty resolving an antibody mixture. One of the antibodies is anti-Le^a. This antibody is not clinically significant in this situation, but needs to be removed to reveal the possible presence of an underlying antibody of clinical significance. What can be done?
Neutralize the serum with saliva
What type of blood should be given to an individual who has an anti-Le^b that reacts 1+ at the IAT phase
Blood that is negative for the Le^b antigen
Which of the following statements is true concerning the MN genotype?
Dosage effect may be seen for both M and N antigens
Anti-M is sometimes found with reactivity detected at the immediate spin phase that persists in strength to the IAT phase. What is the main testing problem with a strong anti-M?
Anti-M may not allow detection of a clinically significant antibody
A patient is suspected of having paroxysmal cold hemoglobinuria. Which pattern of reactivity is characteristic of the Donath-Landsteiner antibody, which causes this condition?
The antibody attaches to RBCs at 4 degrees and causes hemolysis at 37 degrees
How can interfering anti-P1 antibody be removed from a mixture of antibodies?
Neutralization with hyatid cyst fluid
Which antibody is frequently seen in patients with warm autoimmune hemolytic anemia?
An antibody shoes strong reactions in all test phases. All screen and panel cells are positive. The serum is then tested with a cord cell and the reaction is negative. What antibody is suspected?
Which group of antibodies is commonly found as cold agglutinins?
Anti-M and anti-N
Which of the antibodies characteristically gives a retractile mixed-field appearance?
What does the 3+3 rule ascertain?
95% confidence that the correct antibody has been identified
The k (Cellano) antigen is a high-frequency antigen and is found on most red cells. How often would on eexpect to find the corresponding antibody?
Rarely, because most individuals have the antigen and therefore would not develop the antibody
Which procedure would help distinguish between an anti-e and anti-Fy^a in an antibody mixture?
Run an enzyme panel
Which characteristics are true of all three of the following antibodies: anti-Fy^a, anti-Jk^a, and anti-K?
Detected at the IAT phase; may cause hemolytic transfusion reactions
A patient is admitted to the hospital. Medical records indicate that the patient has a history of anti-Jk^a. When you performed the type and screen, the type was O pos and the screen was negative. You should:
Crossmatch using units negative for Jk^a antigen.
A tech performs an antibody study and finds 1+ and weak positive reactions for several of the panel cells. The reactions do not fit a pattern. Several selected panels and a patient phenotype do is diluted and retested, but the same reactions persist. What type of antibody may be causing these results?
High titer low avidity
An antibody is detected in a pregnant woman and is suspected of being the cause of fetal distress. The antibody reacts at the IAT phase but does not react with DTT-treated cells. This antibody causes in vitro hemolysis. What is the most likely antibody specificity?
What sample is best for detecting complement-dependent antibodies?
Serum stored at 4 degrees for not longer than 48 hours
Which antibody would not be detected by group O screening cells?
An ER trauma patient requires transfusion. Six units of blood are ordered stat. There is no time to draw a patient sample. O-neg blood is released. When will compatibility testing be performed?
When the patient sample is available
How would autoantibodies affect compatibility testing?
ABO, Rh, antibody screen and crossmatch may show abnormal results
An antibody screen is reactive at IAT phase of testing using a three-cell screen and the autocontrol is negative. What is a possible explanation for these results?
High-frequency alloantibody or a mixture of alloantibodies
What does a minor crossmatch consist of?
Recipient red cells and donor plasma
Can crossmatching be performed on October 14th using a patient sample drawn on October 12th?
Yes a new sample would not be needed
A type and screen was performed on a 32-year-old woman, and the patient was typed as AB negative. There are no AB-negative units in the blood bank. What should be done?
Check inventory of A-, B-, and O-negative units
What ABO types may donate to any other ABO type?
What types of red cells are acceptable to transfuse to an O-neg patient?
A technologist removed 4 units of blood from the blood bank refrigerator and placed them on the counter. A clerk was waiting to take the units for transfusion. As she checked the paperwork, she noticed that one of the units was leaking onto the counter. What should she do?
Discard the unit
A donor was found to contain anti-K using pilot tubes from the collection procedure. How would this affect the compatibility test?
Compatibility testing would not be affected.
Which is not a requirement for the electronic crossmatch?
There are concordant results od at least one determination of the patients ABO type on file
A patient showed positive results with screening cells and 4 donor units. The patient autocontrol was negative. What is the most likely antibody?
Screening cells and major crossmatch are positive on IS only, and the autocontrol is negative. Identify the problem/
Six units are crossmatched. Five units are compatible, onw unit is incompatible, and the recipient's antibody screen is negative. Identify the problem:
Donor unit may have a positive DAT
An incompatible donor unit is found to have a positive DAT. What should be done?
Discard the unit
Screening cells, major crossmatch, and patient autocontrol are positive in all phases. Identify the problem.
Abnormal protein or nonspecific antibody
All panel study has revealed the presence of patient alloantibodies. What is the first step in major crossmatch?
Antigen type patient cells and any donor cells to be crossmatched
What is the disposition of a donor red blood cell unit that contains an antibody?
The unit may be labeled indicating it contains antibody and released into inventory
Given a situation where screening cells, major crossmatch, autocontrol, and DAT are all positive, what procedure should be performed next?
Elution followed by a cell panel on the eluate
A major crossmatch and screening cells are 2+ at IS, 1+ at 37, and neg at the IAT phase. Identify the most likely problem.
What corrective action should be taken when rouleaux causes positive test results?
Perform a saline replacement technique
What is not a reason for performing adsorption?
Identification of antibodies causing a positive DAT
How long must a recipient sample be kept in the blood bank following compatibility testing?
What is the crossmatching protocol for platelets and or plasma?
No testing required
What are the compatibility requirements for an autologous unit?
ABO and Rh typing
A patient types as AB positive. Two units of blood have been ordered by the physician. Currently, the inventory shows no AB units, 10 A pos units, 1 A neg, 5 B pos, and 20 O pos units. Which should be set up for the major crossmatch?
Which of the following comprises an abbreviated crossmatch?
ABO, Rh, antibody screen, IS crossmatch
When may an IS crossmatch be performed?
When there is no history of antibodies and the current antibody screen is negative.
A patient has a transfusion reaction to packed cells. The tech began the investigation by pre- and post-transfusion specimens and all paperwork and computer printouts. What should he do next?
Check for clerical errors
What is the pathophysiological cause surrounding anaphylactic and anaphylactoid reactions?
Patient is deficient in IgA and develops IgA antibodies via sensitization from transfusion or pregnancy
A patient has a hemolytic reaction to blood transfused 8 days ago. What is the most likely cause?
Delayed immunologic, probably due to an antibody such as anti-Jk^a
What may be found in the serum of a person who is exhibiting the signs of TRALI (Transfusion-related acute lung injury)?
Which type of transfusion reaction occurs in about 1% of all transfusions, results in a temp rise of 1 degree or higher, is associated with blood component transfusion, and is not related to the patient's medical condition?
Febrile nonhemolytic reaction
What would be the result of group A blood given to an O patient?
Immediate hemolytic transfusion reaction
What is not part of the preliminary evaluation of a transfusion reaction?
Panel on pre- and post-transfusion samples
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