Ebook Immunohematology and transfusion medicine - A case study approach: Part 2
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Chapter 14
Playing with Enzymes
Clinical History
A 70-year-old female of African American decent, with history of hypertension,
type 2 diabetes mellitus, anemia, and congestive heart failure, is admitted to the
hospital because of symptomatic anemia (hemoglobin, Hgb level 7.2 g/dL). The
patient has a history of red blood cell (RBC) transfusions and is known to have
alloantibodies (anti-C, -K, and -Fya). The patient was last transfused two units of
RBCs 2 weeks ago. Two RBC units are now requested, and a type and crossmatch
sample (ethylenediaminetetraacetic acid, EDTA anticoagulant) is submitted to the
blood bank.
ABO/Rh/Antibody Screen
ABO/Rh (gel method)
Patient RBCs (forward typing)
Anti-A
Anti-B
Anti-D
0
0
4+
Antibody screen (gel method)
SC1
2+
SC2
2+
Reaction scale = 0 (no reaction) to 4+ (strong reaction)
RBC red blood cell
Patient plasma (reverse typing)
A1 cells
B cells
4+
4+
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© Springer International Publishing Switzerland 2016
M. T. Friedman et al., Immunohematology and Transfusion Medicine,
DOI 10.1007/978-3-319-22342-1_14
67
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14 Playing with Enzymes
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70
14 Playing with Enzymes
Questions
1. Why are the two selected antigen-negative donor units incompatible?
2. What is the significance of the positive autocontrol and direct antiglobulin test
(DAT) results?
3. Why is a selected-cell panel used in this case?
4. What do the antibody panels show? What is the significance of the Fya/Fyb
phenotype?
5. What is the significance of the Jka/Jkb phenotype?
6. What is the significance of the panel results of the enzyme-treated cells?
7. In light of the findings, how would you manage this patient’s transfusion needs?
Answers
1. Why are the two selected antigen-negative donor units incompatible? The
patient has developed one or more new alloantibodies.
2. What is the significance of the positive autocontrol and DAT results? The
newly developed alloantibodies are coating donor RBCs transfused 2 weeks ago,
causing the autocontrol and immunoglobulin G (IgG) DAT to be positive and
resulting in delayed (i.e., extravascular) hemolysis.
3. Why is a selected-cell panel used in this case? Panel cells are selected in this
case to minimize positive reactions with antigens to which the patient is already
known to be sensitized to (anti-C, -K, -Fya). Thus, all cells in the selected panel
are negative for antigens C, K, and Fya.
4.What do the antibody panels show? What is the significance of the Fya/
Fyb phenotype? The antibody panels show that the patient has developed anti-S
antibody which is coating the RBCs as evidenced by the finding of anti-S antibody in the eluate panel. In addition, the selected-cell panel shows antibody with
specificity to anti-Fyb; since this antibody reactivity is not removed by enzyme
treatment (which would be expected of antibody to Fya or Fyb) and in light of the
fact that the patient’s phenotype is negative for both Fya and Fyb antigens, it is
likely that the patient has anti-Fy3 antibody (which is not weakened by enzyme
treatment). It should be noted that the Fya-negative/Fyb-negative antigen phenotype has a high incidence in the African American population owing to resistance
of this phenotype to the Plasmodium vivax malarial parasite. In this population,
the most common reason for this phenotype is the presence of the GATA-box
promoter mutation that causes Fyb antigen to be absent from red cell membranes,
but expressed on other tissues. Therefore, African American patients who are Fya
negative/Fyb negative by serologic typing do not make anti-Fyb and only rarely
make anti-Fy3 [1, 2].
5. What is the significance of the Jka/Jkb phenotype? Antibodies to Jka and Jkb
cannot be ruled out on the selected-cell panel since nonreactive cell (cell # 4) is
heterozygous (i.e., Jka and Jkb antigen positive; antibodies to Jka and Jkb should
References
71
be ruled out only using homozygous cells). Cell # 8 (homozygous for Jkb antigen) does provide some evidence, though, that anti-Jkb is not present since the
antibody reactivity is eliminated by ficin (Jka and Jkb antigens are not sensitive to
the enzyme). However, since the patient is positive for both Jka and Jkb antigens
(phenotype results), the antibodies can be excluded.
6.What is the significance of the panel results of the enzyme-treated cells?
Anti-S reactivity with ficin-treated cells is decreased while anti-Fy3 reactivity is
preserved. It is helpful to remember which antigens are resistant and which are
sensitive to enzyme (ficin, papain, trypsin) treatment. Generally, a way to recall
this is to use the names: “Lewis P. Kidd, PhD” and “M.N.S. Duffy.” The former
refers to the Lewis, P, Kidd, and Rh blood group antigens which are resistant,
while the latter refer to the MNSs and Duffy blood group antigens which are sensitive (though, as noted, the Fy3 antigen is an exception). In addition, it is useful
to know that the Kell blood group antigens are not affected by enzyme treatment
but can be reduced by treatment with dithiothreitol (DTT), a reducing substance
which cleaves disulfide bonds.
7.In light of the findings, how would you manage this patient’s transfusion
needs? In addition to antigen-negative RBCs for previously identified alloantibodies (anti-C, -K, and -Fya), the patient also needs RBCs that are negative
for S antigen and Fy3 antigen (RBCs lacking Fy3 antigen also lack Fya and Fyb
antigens). Although it is not known whether the previously identified anti-Fya
is truly present in the patient’s serum or whether the Fya specificity was just
part of the now-apparent anti-Fy3, this is a moot point since the patient will be
transfused with RBCs lacking Fya and Fyb antigens (which are negative for Fy3
antigen).
References
1. Parasol N, Reid ME, Rios M, Castilho L, Harari I, Kosower N. A novel mutation in the coding
sequence of the FY*B allele of the Duffy chemokine receptor gene is associated with an altered
erythrocyte phenotype. Blood. 1998;92(7):2237–43.
2. Yazdanbakhsh K, Rios M, Storry JR, Kosower N, Parasol N, Chaudhuri A, Reid ME. Molecular
mechanisms that lead to reduced expression of Duffy antigens. Transfusion. 2000;40(3):
310–20.
Chapter 15
The Platelet Transfusion
Clinical History
A 55-year-old male with a history of alcohol abuse and liver cirrhosis presents
to the emergency department with upper gastrointestinal bleeding and symptomatic anemia related to acute blood loss (hemoglobin, Hgb level 7.1 g/dL). A type
and crossmatch sample (ethylenediaminetetraacetic acid, EDTA anticoagulant) is
submitted to the blood bank.
ABO/Rh/Antibody Screen
ABO/Rh (gel method)
Patient RBCs (forward typing)
Anti-A
Anti-B
Anti-D
4+
0
0
Antibody screen (gel method)
SC1
0
SC2
0
Reaction scale = 0 (no reaction) to 4+ (strong reaction)
RBC red blood cell, SC screen cell
Patient plasma (reverse typing)
A1 cells
B cells
0
4+
Additional History
The patient, who has no prior history of transfusion, is transfused two units of
A-negative RBCs by immediate spin crossmatch. He is additionally transfused a
unit of O-positive apheresis (single donor) platelets because of thrombocytopenia
(platelets 30 K/µL). During transfusion of the platelet unit, the patient develops
© Springer International Publishing Switzerland 2016
M. T. Friedman et al., Immunohematology and Transfusion Medicine,
DOI 10.1007/978-3-319-22342-1_15
73
74
15 The Platelet Transfusion
shaking chills, and the transfusion is discontinued after approximately three quarters (200 mL) of the unit has been given (there is slight elevation of the temperature
(T 99.8°F), blood pressure remains unchanged at 130/70 mmHg, pulse slightly increased to 96/min from pre-transfusion values). Posttransfusion samples are sent for
transfusion reaction workup.
Test Results: Posttransfusion Sample
Clerical check
Patient: A negative
Visual check: no hemolysis
Polyspecific
IgG
DAT (pre-sample)
0
0
DAT (post-sample)
2+
2+
DAT direct antiglobulin test, IgG immunoglobulin G
Donor unit
Apheresis platelet unit O positive
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75
76
15 The Platelet Transfusion
Questions
1.What are the possible causes of the transfusion reaction in this case? What is the
most probable cause?
2.In consideration of the positive direct antiglobulin test (DAT) result in the posttransfusion sample, how do you interpret the results of the eluate panel?
3.What additional testing would you recommend to confirm the suspected cause
of the transfusion reaction?
4. What precautions might have been taken to prevent this reaction?
5.Based on the Rh(D) type of the patient versus the apheresis product type, would
you recommend Rh immune globulin (RhIg; 300 mcg dose) to this patient?
Answers
1. What are the possible causes of the transfusion reaction in this case? What is
the most probable cause? The possibilities include immune hemolytic, febrile
nonhemolytic (i.e., secondary to recipient leukocyte antibodies (antibodies to human leukocyte antigens, anti-HLA) or product cytokines), septic (i.e., bacterial
contamination), and allergic reactions. In addition, the symptoms and signs exhibited (i.e., shaking chills and temperature elevation) may be unrelated to the
platelet transfusion (i.e., may be secondary to the underlying disease state, reaction to medication, catheter sepsis, etc.). In this case, the most probable cause is
a minor hemolytic reaction due to anti-A isoantibodies in the group-O apheresis
platelet product (i.e., incompatible plasma).
2. In consideration of the positive DAT result in the posttransfusion sample,
how do you interpret the results of the eluate panel? Though the DAT is IgG
positive in the posttransfusion sample, the eluate panel is negative reflecting the
fact that anti-A antibodies eluted from the patient’s cells would not react with
group-O panel cells. The three main reasons for a positive IgG DAT with a negative eluate result are listed in Chap. #12 question 1 answer.
3. What additional testing would you recommend to confirm the suspected
cause of the transfusion reaction? Reacting the eluate against group-A1 and
group-B cells would show positive reaction only with the former, and thus, confirm hemolysis from donor anti-A as the cause of the reaction.
4. What precautions might have been taken to prevent this reaction? The reaction could have been prevented in several ways: (1) use of ABO-compatible
apheresis platelets (while this is the best solution to prevention, it may not be
always be feasible since platelets have a short shelf life of only 5 days maximum
and exclusive use of ABO-compatible platelets may lead to higher inventory requirement and wastage of platelet products), (2) processing of ABO-incompatible
Recommended Reading
77
platelets to remove incompatible plasma (while technically achievable, it is a
time-consuming process in which the quality and number of platelets in the
washed product is decreased; additionally, storage time due to concerns of bacterial contamination during the washing process, which is an open system, is
limited to 4 h), and (3) measurement of anti-A1 and anti-B isoantibody titers in
the apheresis product and exclusion of such product if the antibody titer is high
(i.e., anti-A1 or anti-B titer > 100; while this method is relatively simple, it is not
wholly reliable and the cutoff for high isoantibody titer may be variable and arbitrary). Finally, it is advisable to avoid giving platelets with ABO-incompatible
plasma to small children or even adults of small stature/body weight where the
amount of incompatible plasma given is relatively high compared to the patient’s
total whole-blood volume and would be expected to cause significant hemolysis.
5. Based on the Rh(D) type of the patient versus the apheresis product type,
would you recommend RhIg (300 mcg dose) for this patient? RhIg may be
given in this case (either prior to or within 72 h after product administration)
to prevent sensitization to the Rh(D) antigen, though, such administration is far
more critical in the case of a female of childbearing age unlike the 55-year-old
male patient in this case. While platelets themselves do not express Rh antigens,
Rh antigens would be present and potentially immunizing on any RBC contaminants present in the platelet product (though usually not visible contamination; at
least 2 mL of RBCs is necessary for visible contamination).
Recommended Reading
1. Klein HG, Anstee DJ. Haemolytic transfusion reactions. In: Klein HG, Anstee DJ, editors.
Mollison’s blood transfusion in clinical medicine. 12th ed. West Sussex: Wiley; 2014.
p. 458–66.
2. Cid J, Lozano M, Ziman A, West KA, et al. Low incidence of anti-D alloimmunization
following D+ platelet transfusion. The Anti-D alloimmunization after D-incompatible platelet
transfusions (ADAPT) study. Br J Haematol. 2015;168(4):598–603.
Chapter 16
Differential Alloadsorption
Clinical History
A 62-year-old male is admitted with lower gastrointestinal bleeding and symptomatic anemia; his hemoglobin (Hgb) level is 5.0 g/dL. The patient has a known
history of a warm autoantibody but no alloantibodies and was transfused two units
of RBCs 1 month ago at the hospital.
ABO/Rh/Antibody Screen
ABO/Rh (gel method)
Patient RBCs (forward typing)
Anti-A
Anti-B
Anti-D
4 +
0
4 +
Antibody screen (gel method)
SC1
1 +
SC2
1 +
Reaction scale = 0 (no reaction) to 4 + (strong reaction)
RBC red blood cell, SC screen cell
Patient plasma (reverse typing)
A1 cells
B cells
0
4 +
© Springer International Publishing Switzerland 2016
M. T. Friedman et al., Immunohematology and Transfusion Medicine,
DOI 10.1007/978-3-319-22342-1_16
79
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