Blood Bank Reviewing concepts
The frequency of the D-negative phenotype in the population is:
15%
65-year-old woman taking sleep medication at night
Acceptable donors
Which one of the following histories represents an acceptable donor? A. Hct: 39, BP: 110/70, T: 99.8F P:75, age: 40 B: Hct: 37, BP 136/86, T: 98.6F P: 80 Age: 18 C: Hct: 41 BP 90/60, T: 99.4F P: 65 Age: 65 D: Hct: 45 BP 185/90 T: 98.6F P: 78 age: 50
C (Feedback: A, Unacceptable temperature; B, unacceptable hematocrit; D, unacceptable blood pressure)
Dose Bombay have immunodominat sugar?
No, none
Which ABO phenotype selection contains the most H antigen and the least H antigen, respectively, on the red cell's surface?
O, A1B
Reagent to identify the specificity of a red cell antibody
Panel cells
h of the following genotypes is possible for an individual whose red cells react as indicated below except: ANTISERA REACTIONS anti-C + anti-D + anti-E + anti-c + anti-e +
R0r" (Feedback: The R0r' genotype expresses the C, c, D, and e antigens, but it does not express the E antigen)
A patient phenotypes as D+C+E-c-e+. The most likely genotype is:
R1R1
How is RNA different from DNA?
RNA usually exists as a single strand. The sugar ribose is substituted for deoxyribose. The base uracil exists only in RNA
When a gene product is expressed only when it is inherited by both parents
Recessive
Antibody to this antigen demonstrates weak mixed field reactions
Sda antigen
Which of the following statements is true regarding high-protein anti-D reagents?
They have been largely replaced with low protein monoclonal reagents. They contain approximately 20% bovine albumin. They may increase the possibility of a false-positive reaction, requiring the use of a control.
Red cells that phenotype as S-s- are also:
U-negative
Antigen of high incidence; antibody to it can cause severe transfusion reactions
Vel
Antigen has a higher frequency in females
Xga
A person whose red cells type as M+, N+ with antisera would be:
a heterozygote (Feedback: Because M and N are alleles, the inheritance of both alleles makes the individual a heterozygote)
Polyspecific antihuman globulin contains:
anti-IgG and anti-C3d
DTT (dithiothreitol) would be useful in the identification of which of the following antibodies?
anti-Kpb
Your blood bank mistakenly transfused 1 unit of D-positive red blood cells to a patient who was typed as D-negative. The patient had no history of a previous transfusion or pregnancy. Antibody detection testing was negative in pretransfusion testing. The crossmatch in this case was:
compatible at immediate spin. (Feedback: The abbreviated or full crossmatch would not have detected this error because anti-D had not been formed and the unit would have been compatible)
The next step in investigating a positive direct antiglobulin test using polyspecific antihuman globulin reagent should be to:
repeat the direct antiglobulin test using monospecific anti-IgG and anti-C3 reagents
Lewis system antibodies have not been implicated in hemolytic disease of the fetus and newborn because:
the antigens are not fully developed at birth, Lewis system antibodies do not cross the placenta, the antibodies are not clinically significant.
What is the minimum hemoglobin level for a potential allogeneic donor?
12.5 g/dL (Feedback: Minimum hemoglobin is 12.5 g/dL for both male and female donors)
How long must a donor wait to donate red blood cells again following a 2-unit red blood cell apheresis donation?
16 weeks
Following centrifugation of the gel card, red cells are observed to be evenly dispersed throughout one of the microtubes. This reaction could be graded as a:
2+
What percentage of the group A population are type A2?
20%
If the recipient was transfused within the last 3 months, how long from the time of collection can a sample be used for the crossmatch?
3 days
In which phase of reactivity would rouleaux typically be detected in the screen?
37 C (Feedback: In the screen, 37 C is typically where rouleaux is initially detected)
The indirect antihuman globulin test is incubated at what temperature?
37C
After adding antigen and antibody to a test tube, one large agglutinate was observed. How should this reaction be graded?
4+
If a prospective donor has participated in a plasmapheresis program, how long must he or she wait to donate whole blood?
48 hours
Allogeneic whole blood donors may donate every __________ days.
56
How long following transfusion must the recipient sample be stored?
7 days (Feedback: The recipient's sample should be stored at 1 to 6 C for 7 days in case there is a transfusion reaction that requires investigation)
Following donation, how long does it take to replace the fluid lost from giving whole blood?
72 hours
How often can a person donate a unit of whole blood for a directed donation?
8 weeks
Approximately what is the percentage of individuals who demonstrate H in their saliva?
80%
Why is the determination of the D antigen important for women during pregnancy?
A D-negative mother should be given Rh Immune Globulin to prevent potential formation (Feedback: D-negative females that are pregnant should be Rh Immune Globulin at 28 weeks to prevent the formation of anti-D, which may cause hemolytic disease of the fetus and newborn on subsequent pregnancies. The exposure to the D antigen on delivery of a D-positive fetus triggers the formation of anti-D. of anti-D during delivery of a D-positive infant)
What ABO phenotype would agglutinate in the presence of anti-A,B produced by group O individuals?
A and B (Feedback: Group O individuals make anti-A,B, an antibody with a specificity to both the A and B antigens)
What is meant by the term autosomal?
A trait that is not carried on the sex chromosomes (Feedback: Autosomal genetic expression is demonstrated in somatic cells, that is, cells in the body that are not gametes)
What substances are found in the saliva of a group A person who also inherited the secretor gene?
A, H
Reagent used in the identification of ABO antibodies
A1 and B cells
A recipient with group A phenotype requires a transfusion of 2 units of frozen plasma. Which of the following types are appropriate to select for transfusion?
AB and A
Antigens of the P system are structurally related to which of the following blood group systems?
ABH
An infant less than 4 months old requires which procedures for compatibility testing?
ABO and D typing and antibody screen initially only; units released without additional testing if the screen is negative (Feedback: An infant less than 4 months old does not make red cell antibodies and therefore does not need to be checked with each transfusion. Initial screens detect antibodies made by the mother)
Reagent used to determine the ABO antigenic composition of a patient's red cells
ABO antisera
The test procedure that combines patient's serum with commercial A1 and B reagent red cells is called:
ABO reverse grouping
In a family study it was determined that all four siblings in the family had a different blood type: A, B, O, and AB. The parents were most likely ____________.
AO and BO (Feedback: Performing a Punnett square demonstrates that a cross between genotypes AO and BO could yield four offspring with different phenotypes)
19-year-old woman who recently finished the three-part vaccination for hepatitis B surface antigen after starting a volunteer position at the hospital
Acceptable donors
28-year-old man who was incarcerated overnight for unspecified reason 2 months ago
Acceptable donors
53-year-old woman taking a beta-blocker for hypertension and over-the-counter low-dose aspirin for blood-clot prevention
Acceptable donors
The subgroup of A with the least amount of A antigen is:
Ael (Feedback: The Ael subgroup requires adsorption and elution procedures to detect the A antigen on the red cells)
Which of the following situations can be found in a classic case of autoimmune hemolytic anemia? A) Positive direct antiglobulin test B) False-positive Fya phenotyping C) Crossmatch incompatibility at antihuman globulin D) All of the above
All of the above
One screening cell 1+ at antihuman globulin phase, DAT negative
Alloantibody, IgG
A gene that does not express a detectable product
Amorphic genes
Amplified target sequences of DNA produced by polymerase chain reaction
Amplicon
What forward typing reagent can be used to confirm group O units before placing them in inventory?
Anti-A, B
According to Landsteiner's rule, what ABO antibody will be detected in a group A individual's serum?
Anti-B
Which of the following is responsible for the activation of the classic pathway of complement?
Antibody bound to antigen
For autologous units transfused within the collection facility, which part of the compatibility procedure is not required?
Antibody screen (Feedback: Autologous units are given to the donor and do not require an antibody screen unless nonautologous units are also to be transfused)
Which of the following red cell antigens do proteolytic enzymes destroy?
Antigens Fya and Fyb in the Duffy system
Which of the following is not a cause for temporary deferment of a whole blood donor? A) Aspirin ingestion 12 hours previously B) Rubella injection 1 week previously C) Oral polio vaccine taken 1 week previously D) Hepatitis B immunoglobulin taken 4 weeks previously
Aspirin ingestion 12 hours previously (Feedback: Aspirin is acceptable for whole blood donation. If platelets are prepared from the unit, they cannot be the sole source of platelets for a recipient)
Both screening cells 2+ at antihuman globulin phase, DAT positive, IgG 2+
Autoantibody or transfusion reaction, IgG
Both screening cells positive 1+ at IS, DAT positive, C3 1+
Autoantibody, IgM
It is necessary to mix the unit frequently during the donation process to:
Avoid blood clots by mixing the anticoagulant with the blood
System associated with McLeod phenotype
Bg
How is it genetically possible for a child to phenotype as D-negative?
Both parents are heterozygous D-positive
Select the cell involved in the clearance of viral infected cells, tumor cells, and foreign-tissue grafts.
CD8 cells
ry
CE
Antigens Yta and Ytb are in this system
Cartwright
r'
Ce
Antigen associated with human T-lymphocyte antigen antibodies
Chido
Equal expression of two different inherited genes as in most blood group systems
Codominant genes
Which of the following contributes to permanent rejection status of a donor?
Confirmed positive test for hepatitis B surface antigen 10 years previously (Feedback: A positive test for hepatitis B core antigen is a permanent deferral)
Of the following markers that can be used to test for paternity, which marker provides the most useful statistical value? A) Human leukocyte antigen typing B) D antigens C) ABO system antigens D) The Kidd system (Jka, Jkb)
D antigens
How would a donor who tested negative with anti-D reagent in the immediate spin test but positive at antihuman globulin with anti-D reagent be labeled?
D-positive
The LW antigen expression is typically stronger on __________ cells.
D-positive red
Rz
DCE
R1r
DCce
R1R1
DCe
R2R2
DcE
R0
Dce
Incubation step is not necessary
Direct antiglobulin test
Which of the following tests is not included in routine compatibility testing? A) Direct antiglobulin test B) ABO phenotyping C) Antibody screen D) D typing A) Direct antiglobulin test B) ABO phenotyping C) Antibody screen D) D typing
Direct antiglobulin test
tests for certain clinical conditions such as hemolytic disease of the newborn and autoimmune hemolytic anemia
Direct antiglobulin test
To distinguish between an A1 and A2 blood type, which reagent is used?
Dolichos biflorus lectin (Feedback: A1 lectin will agglutinate A1 red cells, not A2 red cells)
What are the two components of the major crossmatch?
Donor red cells and recipient serum
Antibodies to which of the following blood group system show dosage (i.e., are stronger with homozygous expression of the antigen)? A) Lutheran B) P C) Duffy D) Kell
Duffy
System associated with resistance to malaria
Duffy
Parents who are both phenotyped as group A cannot have a group O child True or False
False
What portion of the antibody molecule binds to receptors on macrophages and assists in the removal of antibody bound to red cells?
Fc fragment
Which of the following phenotypes is heterozygous? A) Fy(a-b+) B) Jk(a+b-) C) Fy(a+b+) D) Le(a+b-)
Fy(a+b+)
Which of the following blood products requires a crossmatch to be performed before issuing?
Granulocyte concentrates that have more than 2 mL of red blood cells (Feedback: Granulocytes may contain a significant amount of red blood cells because they are obtained from the "buffy coat" layer during apheresis. These units would require crossmatching before release) Feedback: Granulocytes may contain a significant amount of red blood cells because they are obtained from the "buffy coat" layer during apheresis. These units would require crossmatching before release.
N-acetylgalactosamine
Group A
A group A man marries a group AB woman. The father of the group A man was group O. What possible ABO phenotypes could be expected in the offspring?
Group A, B and AB
A patient's red cells are agglutinated by anti-B, but not by anti-A. This person would have which of the following ABO phenotypes?
Group B
D-galactose
Group B
Which of the following situations is most likely to cause intravascular hemolysis when an incompatible transfusion is given?
Group B packed cells to a group O recipient
Given the following ABO phenotyping data: FORWARD Anti-A: 2+mf Anti-B: 0 REVERSE A1 Cells: 0 B cells: 3+ What could be a plausible explanation for this discrepancy?
Group O blood products given to group A (Feedback: Mixed-field reactions are often caused by transfusion of group O red cells, which may take place during an emergency or inventory issue)
L-fucose
Group O, H antigen
When two genes are close together on the same chromosome and are inherited as a "group" or "bundle," they are inherited as this
Haplotypes
Select the term that is associated with the B-cell response to antigens
Humoral immunity
The binding of two complementary pairs of DNA
Hybridization
Cold autoantibodies are typically of which specificity?
I (Cold autoantibodies are typically of the specificity anti-I. I is a high-frequency antigen found on all adult red cells but is absent on cord red cells)
Most Rh system antibodies are of which immunoglobulin class?
IgG
What immunoglobulin class is capable of crossing the placenta?
IgG
What immunoglobulin class reacts best by antiglobulin testing?
IgG
K1-positive donor red cells were mistakenly transfused to a recipient with anti-K. The patient's posttransfusion blood sample has a positive direct antiglobulin test with polyspecific antihuman globulin. The direct antiglobulin test is positive because anti-K is an __________ antibody that has sensitized the __________ cells in vivo.
IgG, donor's
Antibodies detected in the immediate spin crossmatch are usually of which of the following immunoglobulin classes?
IgM
What immunoglobulin class reacts best at room temperature at immediate spin?
IgM
Most "naturally occurring" ABO system antibodies fall into which class?
IgM (Feedback: ABO system antibodies are in the IgM class, which can agglutinate at immediate spin and activate the complement cascade)
A group O patient was crossmatched with group B red blood cells. What phase of the crossmatch will first detect this incompatibility?
Immediate spin (Feedback: ABO incompatibilities should be detected on immediate spin)
To increase the sensitivity of the antibody screen in a compatibility test, what can be done?
Increase the serum to cell ratio. Use an enhancement such as polyethylene glycol. Extend the incubation time
Select the appropriate strategy if the results of red cell and serum testing in the ABO typing procedure have negative agglutination reactions.
Incubate tubes at room temperature or 4C with an autocontrol (Feedback: ABO antibodies are stronger at room temperature or lower. The autocontrol determines whether the enhanced antibody reaction was due to the ABO antibodies or to a cold reacting antibody. The autocontrol should be negative for the ABO typing to be valid)
Anti-D, anti-K, and anti-Jka are the antibodies that are tentatively identified on a panel after initially ruling out on negative cells. What selected cell from another panel should be chosen to confirm the presence of anti-K?
K+, D-, Jk(a-)
Antibodies in this system often fall below detectable levels and are associated with delayed transfusion reactions
Kidd
System associated with chronic granulomatous disease
Knops
All the following antigens are commonly found on screening cells except: A) D. B) k. C) Kpa. D) C.
Kpa
A person who inherits the Le, Se, and H genes will have red cells that phenotype:
Le (a-b+)
Reagent derived from plants used to distinguish group A1 from group A2 red cells
Lectins
Which of the following facts is not a characteristic of Kell system antibodies? A) Usually clinically significant IgG antibodies B) Best detected in indirect antiglobulin test phases C) Lose reactivity with proteolytic enzyme reagents D) Do not bind complement proteins
Lose reactivity with proteolytic enzyme reagents
Antibodies to Lub antigen are not commonly detected because:
Lub antigen is of high incidence
Select the cell involved in acquired immunity.
Lymphocytes
System associated with glycophorin A and B
MNSs
What cells are also known as antigen-presenting cells
Macrophages
To what does the abbreviation "MSBOS" refer?
Maximum blood order schedule
Which condition is often associated with the presence of anti-I?
Mycoplasma pneumoniae infections
What would be the agglutination reaction of red cells from a Bombay phenotype with anti-H lectin?
Negative
When group O blood is not available for transfusion, what is the next alternative?
None (Feedback: Group O individual has both anti-A and anti-B present in serum, which is incompatible with all blood groups other than group O)
The children of an AB mother and a B father could phenotype as all of the following except:
O (Feedback: Unless there was a rare cis AB inheritance pattern, an AB parent would not likely have a group O child)
Technique used to replicate a specific targeted DNA sequence
Polymerase chain reaction
Having two or more alleles at a given gene locus,
Polymorphic
Short segment of DNA with a known sequence that can be labeled with a marker
Probe
DNA fragments produced by enzymatic cleavage at specific recognition sites
Restriction fragment-length polymorphism
Current theory regarding the genetics of the Rh system suggests that:
Rh system antigens are coded by two closely linked genes
Reagent to detect the presence of red cell antibodies
Screening cells
A 58-year-old woman revealed that she had experimented with intravenous drugs as a teenager. What would be the acceptable deferral period, if any, for this potential donor?
She is deferred
The evidence for reagent red cell deterioration may include which of the following?
Spontaneous agglutination, significant hemolysis, loss of agglutination strength over time
18-year-old woman currently taking Accutane for acne
Temporarily deferred
22-year-old man who returned from Iraq 3 months ago and was vaccinated for tetanus and yellow fever before being deployed
Temporarily deferred
25-year-old man treated for syphilis 3 months ago,
Temporarily deferred
27-year-old woman returning from the Peace Corps in Nigeria who was vaccinated for typhoid 6 months ago,
Temporarily deferred
48-year-old man taking Propecia for baldness
Temporarily deferred
50-year-old woman on vacation in the United States who currently lives in England,
Temporarily deferred
Why is incubation omitted in the direct antihuman globulin test?
The antigen-antibody complex has already formed in vivo
During the donor screening process, the potential donor's blood drop sinks to the bottom of the copper sulfate solution within 15 seconds. What is the interpretation of this test?
The donor has an acceptable hemoglobin and hematocrit to donate (Feedback: Using the specific gravity of a copper sulfate solution is a screening method to determine whether the hemoglobin and hematocrit are within limits. If the blood drop does not sink within 15 seconds, the donor's hemoglobin or hematocrit should be verified with a more precise measurement)
When using the Hardy-Weinberg equation to calculate genetic frequencies, which of the following must be true?
The population statistics must be large. Mutations cannot occur. Mating must be random
Select the correct statement regarding the collection of a blood sample for compatibility testing.
The sample must be labeled at the bedside
Why is it sometimes necessary to distinguish A1 and A2 blood types?
To resolve a discrepancy between the forward and reverse typing (Feedback: Routine testing with anti-A1 lectin is necessary to resolve a discrepancy between the forward and reverse typing. Individuals who possess the A2 antigen can make anti-A1 antibody)
In an antibody identification panel, only one red cell was negative at the antihuman globulin phase. On ruling out and matching the pattern, an anti-k was identified. What further testing is necessary to confirm the antibody?
Two more k-negative cells should be tested (To satisfy the "rule of three," three negative and three positive reactions for the antigen should be observed to rule in an antibody)
Anti-D reagent and the Rh control were tested with red cells. Both tests were 2+ agglutination reactions. What is the interpretation of the results?
Unable to interpret without further testing
A father carries the Xga blood group trait and passes it on to all of his daughters but to none of his sons. What type of inheritance pattern does this demonstrate?
X-linked dominant (Feedback: Because the father passed the trait to only his daughters, it was carried on the X chromosome. Because only one is needed for expression, this is a dominant genetic trait)
In the solid-phase red cell adherence test, a negative test would appear as:
a button of cells on the bottom of the well
An advantage of the polymerase chain reaction for viral marker testing is:
a small amount of DNA or RNA can be detected
The weak D test detects:
a weak D antigen
Blood collected from a therapeutic phlebotomy is:
acceptable for inventory under certain Food and Drug Administration guidelines. (Feedback: The Food and Drug Administration requires a variance from the blood center to allow a blood unit from a donor with genetic hemochromatosis to be placed into inventory)
An advantage of using a monoclonal antibody over a polyclonal antibody includes all of the following except:
all variations of the antigen can be detected
An antibody with a specificity other than to one's own cells or tissue that is stimulated by transfusion or pregnancy is termed an:
alloantibody
Both screening cells positive 1+ at IS, DAT negative
alloantibody, IgM
The Donath-Landsteiner antibody is:
an IgG auto anti-P
In the process of identifying an antibody, the technologist observed 2+ reactions with 3 of the 10 cells in a panel at the immediate spin phase. These reactions disappeared following incubation at 37 C and the antihuman globulin phase of testing. The antibody most likely to be responsible is:
anti-I
If all red cells tested at room temperature are positive with a patient's serum except for cord cells, the probably antibody identity is:
anti-I (The I antigen is found on adult red cells, not on cord red cells. Anti-I reacts best at colder temperatures)
The following red cell antigen frequencies: K 10% E 30% K 90% P1 80% Which of the following red cell alloantibodies would be responsible for incompatible crossmatches with one 1 of 10 random donor units?
anti-K (Feedback: Anti-K is incompatible with 1 in 10 units of red blood cells)
An example of a cold alloantibody includes:
anti-M
The following statements regarding anti-P1 are true except:
anti-P1 will not react with enzyme-treated P1 positive red cells (Feedback: Anti-P1 is an IgM alloantibody that is made by P2 individuals and reacts best at colder temperatures)
Antibodies to low-incidence antigens include all of the following except: A) anti-Vel. B) anti-Cw. C) anti-V. D) anti-Lua.
anti-Vel
A recipient phenotypes as group O with the following Rh phenotype: D+C+c-E+e+.If this recipient is transfused with red blood cells from six random group O D-positive donors, what Rh alloantibody could this patient produce as a result of transfusion?
anti-c (Feedback: Although Rh phenotyping is not routinely performed, exposure to the c antigen may cause the recipient to make anti-c because the recipient is negative for the antigen)
An anti-E was identified in a patient who recently received a transfusion. What other Rh system antibody should be investigated
anti-c (Feedback: Anti-c is often found in patients who make anti-E. Anti-c is often weaker and shows dosage when the patient is developing the antibody from the first exposure to the antigen)
In a serologic test, the term prozone is also known as:
antibody excess
If all the panel cells were reactive at the same strength at the antihuman globulin phase, no negative reactions were observed, and the autocontrol was negative, what should be suspected?
antibody to a high-frequency antigen
Select the test that uses IgG-sensitized red cells (check cells).
antiglobulin test
Patient M.M. was admitted to the hospital with acute bleeding. Anti-E was detected in the patient's serum. Four E-negative units of blood were crossmatched for the patient. The units were compatible at immediate spin and following the antiglobulin test. After the antiglobulin test was performed, IgG sensitized red cells gave a 2+ agglutination reaction. The proper interpretation of this 2+ agglutination reaction is the:
antihuman globulin washing procedures was adequate (Feedback: IgG-sensitized red cells should be positive if adequate washing was performed and antihuman globulin reagent was added)
Autologous donors may not donate if they:
are on antibiotics for an infection (Feedback: A risk of bacteremia would cause the autologous donor to be deferred)
In a lymphocytotoxicity test, cells that take on the dye:
are recognized by a specific antibody
Detect IgG or complement-coated red cells
both the direct and indirect antiglobulin test
Requires washing the cells several times before the addition of antihuman globulin reagent
both the direct and indirect antiglobulin test
The numeric Rh4 nomenclature refers to which antigen in the Rosenfield notation?
c (Feedback: The more common Rh system antigens are Rh1 = D, Rh2 = C, Rh3 = E, Rh4 = c, Rh5 = e)
rr
ce
The purpose of adding antibody-sensitized red cells following the antiglobulin test is to:
check that the wash procedure was sufficient to remove unbound antibodies
Antibody screening cells are positive at the antihuman globulin phase of testing. The first step of the investigation should be to:
check transfusion and pregnancy history
The inheritance of the Rh antigens are:
codominant
Select the portion of the antibody molecule that imparts the antibody's unique class function.
constant region of the heavy chain
What is the most important concern when trying to identify antibodies in a patient with a warm autoantibody?
determining whether there are underlying alloantibodies
The best description of the elution technique is that it is a technique used to:
disassociate IgG antibodies from red cells for further identification (Feedback: Elution procedures remove IgG antibodies from sensitized red cells to be used for identification using panel cells)
The use of the electronic (computer) crossmatch is restricted to recipients who:
do not have clinically significant antibody (Feedback: The electronic (computer) crossmatch may be performed only on patients who do not have or have a history of a clinically significant antibody)
All the following statements are true regarding Lewis system antibodies except antibodies: A) may be observed at the immediate spin, 37° C, and antihuman globulin phases. B) can be neutralized by Lewis substance. C) may cause hemolysis in vitro. D) do not react following enzyme treatment of cells.
do not react following enzyme treatment of cells
Antibodies to Kidd, Kell, and Duffy blood group antigens share all the following characteristics except:
enhanced with enzyme treatment
What is the potential effect in a tube agglutination test if a red cell suspension with a concentration greater than 5% is used?
false negatives
Select the method that uses a dextran-acrylamide matrix.
gel technology
The immediate spin or abbreviated crossmatch is an acceptable procedure if the recipient:
has no prior or existing clinically significant antibodies
The major histocompatibility complex is located on chromosome 6 and is important in all the following immune functions except:
hemolysis
In which of the following situations can the crossmatch test be omitted?
in a patient who has recieved a massive transfusion within a 24-hour period (Feedback: The performance of a crossmatch for a massively transfused patient may be omitted if the total patient volume has been exchanged (10 to 12 units of whole blood) within 24 hours)
The phase of the agglutination reaction is important in the interpretation of the antibody screen or antibody identification panel because it
indicates the class of antibody
All of the following can cause the D antigen expression to be weaker except:
inheriting the G gene (Feedback: The G gene is always inherited when the D or C gene is inherited and has no effect on the strength of the D gene)
An anti-Fya was identified in a patient's serum. The patient's red cells phenotyped as Fya positive using commercial antisera. The next step is to:
investigate a recent transfusion history (The patient's red cells should be Fya negative to make anti-Fya unless a recent transfusion was given of Fya positive red cells. If no Fya-positive red cells were recently transfused, the antibody identified may be incorrect or the patient may have a positive direct antiglobulin test)
The gel technology method uses a concentration of red cells that is:
lower than tube techniques
Crossing over occurs during:
meiosis (Feedback: Crossing over is the sharing of chromosomal material during meiosis and contributes to greater genetic variation among offspring)
All of the following may be used to perform an antibody screen for an infant less than 4 months old except:
paternal serum
An autoadsorption uses what type of cells to remove antibody from the serum?
patient red cells (Patient red cells are treated to remove IgG antibody and then are incubated with the patient's serum to remove more autoantibodies that are interfering with alloantibody identification)
An antibody screen on a patient with a prior history of transfusion was negative. The crossmatch, performed at immediate spin and antihuman globulin, was incompatible with 1 unit selected. The next step in the investigation would be to:
perform a direct antiglobulin test on the incompatible unit (Feedback: The most likely reason for the incompatibility is that the blood unit has a positive direct antiglobulin test or the patient has developed an antibody to a low-frequency antibody. If the direct antiglobulin test is negative, testing the patient's serum against a selected cell panel of low-frequency antigen positive cells should be performed)
If an anti-I is suspected in a patient's sample that requires a transfusion, the most acceptable course of action is to:
perform the prewarm technique
Testing for the weak D expression is performed by:
performing the indirect antiglobulin test with anti-D (Feedback: The weak D test (previously called the Du test) involves the indirect antiglobulin test using anti-D reagent)
When an individual is said to be group A, it refers to the individual's:
phenotype
Reagent antibodies prepared from human sources are:
polyclonal in specificity
What reagent contains antibodies to multiple antigenic epitopes?
polyclonal-based
Which red cells are used to screen for antibodies in donor samples?
pooled screening cells
Which type of autologous donation procedure is the most common for most types of surgery?
preoperative donation
Compatibility procedures will address all of the following except to:
prevent antibody formation (Feedback: The compatibility test may prevent the formation of anti-D, but all other antigens are not matched)
Product limitations and technical considerations for each reagent can be found in the:
product insert
High-titer, low-avidity antibodies typically:
react with antigens of high frequency in the population
Rh system antibodies characteristically give
reactions that are enhanced with enzymes
Antibody screening of the recipient is performed as a component of compatibility testing to detect:
red cell alloantibodies (Feedback: The antibody screen detects alloantibodies that the recipient made to red cell exposure from pregnancy or prior transfusions)
Human leukocyte antigen antibodies are often stimulated following a patient's repeated transfusions of platelets. This poor response to platelet transfusion is known as:
refractoriness.(Repeated platelet transfusions that contain leukocytes can increase the immune response to human leukocyte antigen and decrease the effectiveness of platelet transfusion.)
If an emergency exists and there is not enough time to perform a crossmatch for red cells, what is the correct procedure?
release group O, D-negative whole blood (Feedback: Group O D-negative red blood cell units should be released and the crossmatch procedure completed as soon as possible)
Which of the following phenotypes will react with anti-f?
rr (Feedback: The f antigen is the expression of the c and e gene complex when they are inherited on the same chromosome. Because the Weiner nomenclature "r" indicates that the ce gene was inherited together, it will express the f antigen)
Which of the following will cause an antigen to elicit a greater immune response?
size greater than 10,000 daltons
Proteolytic enzymes should not be used to screen for antibodies because:
some antigens are destroyed by enzymes, which would cause the antibodies to be missed
The antiglobulin test was performed using gel technology. A button of cells was observed at the bottom of the microtube following centrifugation. This result indicates a:
strong positive reaction
A blood sample from a 90-year-old man was submitted to the blood bank for a type and screen before surgery. The forward type demonstrates as a group A, whereas the reverse type appears to be group AB. The most likely cause of the discrepancy is:
that patient has low-titer isoagglutinins (Feedback: In patients who are older, the level of ABO isoagglutinins can be below detectable levels)
Solid-phase red cell adherence used for antibody detection has an advantage over tube testing because:
the endpoint is more clearly defined
If two traits were found to occur higher in a population together than each occurs separately, they may be linked. This would suggest that:
the genes are close together on the same chromosome
Red cells that phenotype as D-negative indicate that:
there is no genetic material inherited from the RHD gene from both parents (Feedback: The D-negative phenotype is caused by the absence of genetic material at the RHD gene locus. This must be inherited from both parents to result in a negative expression)
Which of the following statements is true regarding IgG-sensitized red cells?
they must be used to confirm a negative antiglobulin tube test
Mitosis results in __________ chromosomes as the original.
two cells with the same number of
How would you interpret the results if both the anti-D reagent and the Rh control were 2+ agglutination reactions?
unable to determine without further testing
Select the region of the antibody molecule responsible for imparting unique antibody specificity.
variable region
Monoclonal antibodies are prepared in:
vitro (Feedback: Monoclonal antibodies are prepared from antibody-producing B lymphocytes and myeloma cells in a hybridoma)
If anti-M was reacted with red cells that are M+N+, how would they compare with red cells that are M+N-?
weaker
An autoadsorption may be performed to investigate underlying autoantibodies. When is this procedure acceptable?
when the patient has not been recently transfused