Clinical Pathology(Bb)

Front 1

All of the following are potential risks in chronic transfusion of sickle cell disease patients, except:
A. iron accumulation
B. infectious disease
C. autoantibody development
D. volume overload
E. stroke

Back 1

E. stroke.
The risk of stroke in sickle cell disease is not due to the chronic transfusions per se, but rather due to the disease itself. Many of the potential risks have been minimized
with the use of chelation and cytapheresis, but some risk remains.
QCCP2, Transfusion in sickle cell disease

Front 2

How much whole blood is one complete dose (300 micrograms) of RhIg capable of protecting against the development of anti-D antibody?
A. 300 mL
B. 100 mL
C. 30 mL
D. 10 mL
E. 1 mL

Back 2

C. 30 mL.
1 vial of RhIg can routinely protect against 30 mL of whole blood, 15 mL of red blood cells, or 5 apheresis platelet units. For this reason, when calculating the dose of
RhIg, one first calculates the amount of fetal blood in circulation (mother blood volume times percentage fetal blood), then divides that amount by 30 to get the number of vials needed to protect against IgG anti-D development.
QCCP2, Rh hemolytic disease of the newborn

Front 3

What is the range of risk reduction for the development of anti-D with the use of prophylactic RhIg?
A. 100% decreased to 50%
B. 100% decreased to 10%
C. 80% decreased to 10%
D. 8% decreased to 0.1%
E. 1% decreased to 0.5%

Back 3

D. 8% to 0.1%.
A single full dose of RhIg - 300 micrograms - delivered at 28 weeks gestation to a Rh-negative mother is capable of decreasing the risk of developing anti-D from 8% to 0.1%.
QCCP2, Rh hemolytic disease of the newbor

Front 4

What is the prime titer decision point for the presence of a clinically-significant anti-D antibody in pregnancy?
A. 1:1000
B. 1:100
C. 1:50
D. 1:16
E. 1:4

Back 4

D. 1:16.
A titer of less than 1:16 is associated with a very low risk of hemolysis. Titers greater than 1:16 become a cause for monitoring fetal hemolysis with either Liley curves
and delta OD450 of amniotic fluid or transcranial Doppler ultrasound blood velocity flow.
QCCP2, Rh hemolytic disease of the newborn

Front 5

What is the most common antigen involved in HDN?
A. Rh
B. ABO
C. Kell
D. c
E. Duffy

Back 5

B. ABO.
Great success has been made with anti-D prophylaxis for Rh-negative women. So much so that ABO incompatibility, especially in A or B children born to O mothers, is the predominant cause of hemolytic disease of the newborn. Luckily, the hemolysis is very mild. Severe HDN is most often due to anti-Kell, followed by anti-c.
QCCP2, Hemolytic disease of the newborn

Front 6

All of the following antibody classes are capable of causing hemolytic disease of the newborn (HDN), except:
A. IgG1
B. IgG2
C. IgG3
D. IgG4
E. all of the above can cause HDN

Back 6

B. IgG2.
In addition to dimeric IgA and pentameric IgM, IgG2 is unable to cause hemolytic disease of the newborn. Like IgA and IgM, IgG2 is unable to cross the placental
membrane and is therefore unable to initiate hemolysis.
QCCP2, Hemolytic disease of the newborn

Front 7

What is the approximate risk of a serious in utero hemorrhage in a fetus affected by neonatal alloimmune thrombocytopenic purpura (NATP)?
A. 0%
B. 1%
C. 10%
D. 50%
E. >90%

Back 7

D. 50%.
The risk of hemorrhage is extremely high, especially intracranial hemorrhage. The treatment of NATP is washed maternal platelets because the maternal platelets are presumably PLA1 negative.
QCCP2, NATP

Front 8

Which of the following antigens is most commonly associated with maternal immune thrombocytopenic purpura?
A. red blood cell glycophorin A
B. platelet GPIIb/IIIa
C. platelet PLA1
D. red blood cell CD59
E. red blood cell GPIIb/IIIa

Back 8

C. platelet PLA1.
Both maternal ITP and neonatal alloimmune thrombocytopenic purpura (NATP) are associated with antibodies directed against the platelet antigen, PLA1. Unlike hemolytic disease of the newborn, neonatal alloimmune thrombocytopenic purpura sensitization and hemolysis can occur in the first pregnancy.
QCCP2, Maternal ITP and NATP

Front 9

All of the following are potential mechanisms for a drug-induced positive DAT, except:
A. immune complex
B. nonimmune protein adsorption
C. true autoimmune hemolytic anemia
D. cold autoantibody
E. drug-hapten mechanism

Back 9

D. cold autoantibody.
A number of drugs are associated with each mechanism and it's helpful to remember 1 or 2 for each mechanism. The prototypical drug for immune complex-mediated
reactions is quinidine. Cephalosporins are known for causing a positive DAT through the immune complex mechanism. Nonimmune protein adsorption is associated with
cephalothin. True autoimmune hemolytic anemia is associated with procainamide and aldomet, while hapten-associated positive DAT is associated with penicillin.
QCCP2, Drug-induced positive DAT

Front 10

Which of the following techniques is suitable for helping to detect potential alloantibody in the presence of a cold autoantibody?
A. perform all tests at 37°C
B. use monospecific anti-IgG AHG reagent instead of polyspecific
C. adsorption of cold autoantibody with autologous red cells
D. A & B
E. A, B, C

Back 10

E. A, B, C.
A cold autoantibody should be worked up. There is a possibility of a high titer antibody that can react over a wide temperature range and be pathologic. All of the above named tests are potential means of alleviating a confounding cold autoantibody.
QCCP2, Blood banking considerations with a cold autoantibody

Front 11

At what temperature does hemolysis occur with paroxysmal cold hemoglobinuria?
A. <0°C
B. 4°C
C. 10°C
D. 20°C
E. 37°C

Back 11

E. 37°C.
The Donath-Landsteiner antibody, first described in syphilis, but now associated with pediatric viral infections, is a unique biphasic antibody that preferentially binds at cold temperatures (such as in the extremities) but then hemolyzes at body temperature (such as when blood from the periphery returns centrally).
QCCP2, Paroxysmal cold hemoglobinuria

Front 12

What are the most common autoantibodies?
A. warm autoantibodies
B. antibodies that cause warm autoimmune hemolytic anemia
C. benign cold autoagglutinins
D. cold antibodies that cause autoimmune hemolytic anemia
E. antibodies that cause cold agglutinin syndrome

Back 12

C. benign cold autoagglutinins.
Benign cold agglutinins, most commonly anti-I, are the most frequent source of autoantibodies. There are some cold-reacting antibodies seen with paroxysmal cold hemoglobinuria that are clinically significant, but for the most part, cold-reacting antibodies are not clinically significant.
QCCP2, Cold-reacting autoantibodies

Front 13

Which of the following grades of RBC agglutination during the AHG phase is most correlated with the chance that hemolysis will occur?
A. m+
B. 1+
C. 3+
D. 4+
E. the risk of hemolysis is not correlated with the grade of agglutination

Back 13

D. 4+.
Most people's first instinct is to state that there is no correlation between the grade of agglutination and the risk of hemolysis. However, it has been shown that the stronger the agglutination, the greater the risk for hemolysis. In addition, detection of strong C3 reaction is correlated with an increased risk of hemolysis.
QCCP2, Warm-reacting antibodies

Front 14

Which of the following questions is the most important one to ask in a patient with a positive DAT?
A. has the patient been recently transfused?
B. has the patient has a recent bone marrow transplant?
C. what medications is the patient taking?
D. is the patient hemolyzing RBCs?
E. is the result a false positive?

Back 14

D. is the patient hemolyzing RBCs?
The very first question that should always be asked when a positive DAT shows up (or in a suspected transfusion reaction) is whether or not the patient's red blood cells
are hemolyzing. The other questions presented, though important, are clearly not as important as ruling out hemolysis.
QCCP2, Autoantibodies

Front 15

Which of the following conditions explains why an A-negative patient with colon cancer can forward type as AB, but have anti-B antibodies on reverse typing?
A. acquired B phenotype
B. anti-Lw antibody
C. AZB phenotype
D. high titer, low-avidity antibodies
E. antibodies to reagents

Back 15

A. acquired B phenotype.
The acquired B phenotype occurs when bacterial deacetylases remove the acetyl group from the A1 antigen, making it resemble somewhat the B antigen. As a result, patients will forward type as having both A and B antigens, but retain their anti-B antibodies. Any condition that could lead to bacteremia can cause acquired B phenotype.
QCCP2, Unusual findings in pre-transfusion testing

Front 16

Which of the following is among the most common cause of a positive crossmatch with a negative antibody screen?
A. anti-C
B. anti-ABO
C. anti-Lea
D. anti-Kell
E. antibodies to reagents

Back 16

B. anti-ABO.
Alloantibodies, such as anti-c, anti-Lea, and anti-Kell, are usually identified on an antibody screen as a cause of a positive crossmatch. The same goes for anti-reagent
antibodies. Anti-ABO is not tested on a routine antibody screen, nor can certain low-incidence antigens. As a result, they both are commonly undetected on an antibody
screen, despite a positive crossmatch.
QCCP2, The positive crossmatch

Front 17

All of the following antigens are enhanced by enzyme digestion, except:
A. Lewis
B. P
C. Rh
D. I/i
E. Fya

Back 17

E. Fy a.
“Lewis is a Rhotten Peeing Kidd” helps me remember the antigens that are enhanced by enzyme treatment.
QCCP2, Other special techniques

Front 18

Which of the following lectins and binding substrates are incorrectly matched?
A. Dolichos biflorus, B
B. Ulex europaeus, H
C. Vicea graminea, N
D. Lotus tetragonolobus, H
E. Bandeiraea simplicifolia, B

Back 18

A. D , B.
I hope that you weren't tricked by this question by not reading it carefully. Read it carefully! The most commonly used lectins (and the ones that you should know) are Ulex europeaus which agglutinates O RBCs and are used to detect secretor patients. Dolichos biflorus, which binds A1, effectively helps to separate A1 from A2 red blood
cells.
QCCP2, T2.9 Neutralization substances and lectins

Front 19

Which of the following neutralizing substance and antigens are correctly matched?
A. hydatid cyst fluid; H
B. breast milk; I
C. saliva; P1
D. pigeon eggs; Lea
E. guinea pig urine; Chido

Back 19

B. breast milk; I.
There are a number of odd substances that one can only believe serendipitously found their way into red cell testing. Both hydatid cyst fluid and pigeon egg fluid can
neutralize the P antigen. Breast milk neutralizes the I antigen, saliva neutralizes H and Lea, guinea pig urine neutralizes Sda, and plasma neutralizes Chido and Rodgers.
QCCP2, T2.9 Neutralizing substances and lectins

Front 20

Which of the following antigens is only made when bacterial neuraminidase activates it?
A. Cad
B. Tn
C. Wra
D. Kpa
E. Gy

Back 20

B. Tn.
Polyagglutination of adult cells can occur when the T (or Tn or Tk) antigens are present. These antigens are revealed by the action of bacterial neuraminidase on the red
cells and are positive for agglutination only in the adult, not in cord serum.
QCCP2, Polyagglutination

Front 21

All of the following are properties of high-titer low-avidity antibodies (HTLA), except:
A. they are directed against high incidence antigens
B. they exhibit irreversible binding to test cells
C. they are usually weakly-reactive to all cells in panel
D. they are still reactive when highly diluted
E. all of the above are features of HTLA

Back 21

B. they exhibit irreversible binding to test cells.HTLA antibodies are usually found as weakly reacting to all the panel cells after AHG is added. This is due to the fact that the antigen is so common that it is present in
all panel cells. In addition, they are usually high-titer so that whenever diluted, they are still reactive. For the most part, their only significance is that they can mask a clinically significant antibody.
QCCP2, Antibodies to high incidence antigens, or HTLA

Front 22

Which of the following antibodies usually displays dosage?
A. Duffy
B. Kidd
C. MNS
D. C/c
E. all of the above

Back 22

E. all of the above.
Certain antibodies very predictably display dosage. The panel can help with the identification of these antibodies. Typically, they will exhibit a stronger reaction to panel
cells that are homozygous for the antigen than against cells that are heterozygous. For example, a Fya antibody will react more strongly against an Fy (a+b-) panel cell
than against an Fy (a+b+) cell.
QCCP2, Nonroutine panel

Front 23

All of the following techniques are useful in the evaluation of the nonroutine antibody panel, except:
A. adsorption
B. high ionic strength saline
C. enzyme incubation
D. neutralization
E. all of the above are commonly used in evaluating nonroutine panels

Back 23

B. high ionic strength saline.
Nonroutine panels may be due to numerous causes - multiple antibodies, antibodies displaying dosage, high-titer low-avidity (HTLA) antibodies, or antibodies against
reagents in the assay. Various techniques have been successfully used to aid with identification - adsorption can be used to selectively remove a confounding antibody,
enzymes can be used to enhance or destroy certain antigens, and neutralization can also be used to remove certain antibodies.
QCCP2, The nonroutine panel

Front 24

Which of the following criteria is most commonly used to establish the identity of a particular alloantibody in a routine antibody panel?
A. positivity with 1 cell, negativity with 1 cell
B. positivity with 5 cells, negativity with 1 cell
C. positivity with 1 cell, negativity with 5 cells
D. positivity with 1 cell, negativity with 3 cells
E. positivity with 3 cells, negativity with 3 cells

Back 24

E. positivity with 3 cells, negativity with 3 cells.
In most instances, a confirmation of the identity of an antibody requires positivity in at least 3 cells with the antigen and negativity with at least 3 cell lines without the
antigen. This of course excludes autoantibodies.
QCCP2, Routine panel

Front 25

Which of the following is considered “clinically significant”?
A. an antibody that causes hemolytic disease of the newborn
B. a warm-reacting IgG antibody
C. a cold-reacting P antigen
D. IgM anti-ABO
E. all of the above

Back 25

B. a warm-reacting IgG antibody.
For the most part, warm-reacting IgG antibodies are clinically significant, while IgM cold-reacting antibodies are usually insignificant. Some notable exceptions include the
IgM anti-ABO and the cold-reacting IgG against the P antigen seen in paroxysmal cold hemoglobinuria.
QCCP2, Clinical significance of detected antibodies

Front 26

Which of the following is added to blood in a direct antiglobulin test?
A. nothing (just incubate at 37°C)
B. antihuman globulin
C. patient serum
D. patient RBCs
E. antibodies of known specificity

Back 26

B. antihuman globulin.
The easiest way to remember the difference (and function) between a direct antiglobulin test (DAT) and an indirect antiglobulin test (IAT) is that a DAT “directly” tests
for the presence of antibodies bound to RBCs by adding antiglobulin. The IAT requires the extra step of adding specific antibodies (serum or purified) prior to the
addition of antiglobulin.

Front 27

Which of the following reactions is considered positive in terms of an antibody panel?
A. agglutination
B. hemolysis
C. coagulation
D. A & B
E. A, B, C

Back 27

D. A & B.
Either hemolysis or agglutination is needed in order to call a reaction positive. Hemolysis is detected by a pink-colored supernatant, while agglutination is graded on a
scale from m+ (microscopic) to 4+.
QCCP2, Types of reactions

Front 28

Class II HLA genes encode proteins found on all the following cell types, except:
A. macrophages
B. megakaryocytes
C. activated T-cells
D. B-cells
E. all of the above express Class II HLA antigens

Back 28

B. megakaryocytes.
While Class I HLA is expressed on virtually all nucleated cells, Class II expression is much more restricted. This is fitting as MHC Class I functions as a “general alarm”
and presentation antigen which can be recognized by potential cytotoxic CD8+ T cells. MHC Class II, however, facilitates humoral and cell-mediated immunity by
recruiting helper CD4+ T cells to “professional” antigen-presenting cells.
QCCP2, HLA

Front 29

All of the following genes are encoded within the major histocompatibility complex, except:
A. HFE
B. TNF
C. PKHD1
D. complement proteins
E. 21-hydroxylase

Back 29

C. PKHD1.
While the gene encoding PKHD1 is located on chromosome 6, it is not located within the major histocompatibility complex like the the genes in the rest of the choices are.
QCCP2, HLA

Front 30

33. The P antigen is significant for a number of varied properties. Which of the following is not one of them?
A. the cause of acquired B phenotype
B. the target of antibodies in paroxysmal cold hemoglobinuria
C. agglutinated by hydatid cyst fluid
D. the receptor for parvovirus B19
E. agglutinated by pigeon egg fluid

Back 30

A. the cause of acquired B phenotype.
There are three major things to remember about P antigens. They are agglutinated by pigeon egg and hydatid cyst fluids. They are receptors for the parvovirus B19.
Finally, they are the target of antibodies that cause paroxysmal cold hemoglobinuria (which should not be confused with paroxysmal nocturnal hemoglobinuria).
QCCP2, P blood group

Front 31

Which blood group antigen is associated with the McLeod phenotype?
A. Kidd
B. Duffy
C. Kell
D. MNS
E. Lutheran

Back 31

C. Kell.
McLeod phenotype is a chronic hemolytic anemia due to RBC structural abnormalities. The Kx gene on the X chromosome encodes a support protein that stabilizes Kell
expression. Without Kx protein, the expression of Kell proteins is greatly diminished. In addition to decreased Kell expression and reduced RBC survival, there is an
association with X-linked chronic granulomatous disease.
QCCP2, Kell blood group

Front 32

Which Duffy phenotype confers resistance to malaria?
A. Fy (a+b+)
B. Fy (a+b-)
C. Fy (a-b+)
D. Fy (a-b-)
E. there is no Duffy phenotype that confers resistance to malaria

Back 32

D. Fy (a-b-).
The absence of Duffy a and b confers resistance to P vivax malaria. The Fy (a-b-) phenotype is found in more than 2/3 of people of African descent, while it is rare
otherwise.
QCCP2, Duffy