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The Effect of Lymphocytotoxic Antibody Reactivity on the Results of Single
Antigen Mismatched Platelet Transfusions to Alloimmunized Patients
By Mohamad A. Hussein, Edward J. Lee, Robert Fletcher, and Charles A. Schiffer
Despite selection strategies that attempt to maximize the
platelet donor pool, significant numbers of alloimmunized
patients have few if any available donors. Although the number of potential donors increases when one antigen mismatched platelet transfusions (OAMPT) are considered,
transfusions from such donors are often cited to fail to produce satisfactory platelet count increments. The presence
of lymphocytotoxic antibody (LCTAB) correlates well with
responsiveness to random donor platelet transfusions and
serves as a good serologic screen for the diagnosis of alloimmunization. We therefore reviewed the results of OAMPT to
alloimmunized patients and assessed the relationship between LCTAB levels in the recipient and posttransfusion
platelet count increments. We noted an unexpectedly high
percentage of good responses in our patient population: 73%
of all OAMFT to recepients with LCTAB 4 0 % reactive, resulted in successful increments. In recipients with LCTAB
>60%, 58% of all transfusions were still successful. Despite
a statistically significant inverse relationship between the
level of LCTAB and the response of OAMPT to alloimmunized patients, 589’0 to 73% of recipients will have a satisfactory platelet recovery posttransfusion. These data support
extending donor searches for alloimmunized patients to include any single mismatch particularly if a recipient‘s LCTAB
has lower reactivity.
0 1996 by The American Society of Hematology.
T
squared) divided by the number of platelets transfused X
A CCI of 27,500 was considered to be an adequate response to
transfusion.” Refractoriness to platelet transfusion was defined as a
posttransfusion CCI of <4,000 to random donor platelet concentrates
on at least two consecutive occasions. All analyzed transfusions
were administered after this defining point. Platelets were stored
as single platelet concentrates at 22°C with horizontal to-and-fro
agitation. The majority of transfused units were stored for no more
than 3 days.
Lymphocytotoxic antibody testing was performed on patients’
serum at the time of hematologic diagnosis and was repeated at
biweekly intervals during treatment, or more frequently if clinically
warranted by changing response to random donor pooled platelet
concentrates. LCTAB was determined as the percent of cytotoxicity
of patients’ serum against a panel of lymphocytes of different antigenicity using standard methods.” Antibody (LCTAB) cytotoxic to
20% of the panel lymphocytes obtained within 2 weeks of a particular transfusion was defined as po~itive.~
A standard linear regression method was used to fit the relationship between CCI values and the corresponding degree of positivity
of the LCTAB percentage. The slope parameter’s P value was determined from a t-distribution and tested for statistical significance.
The only variables used in the regression equation are CCI and
percent LCTAB, where the former is the dependent variable and
the latter is the independent variable. All statistical analyses were
performed using Statistical Analysis Software (SAS Institute, Cary,
NC).
HE MANAGEMENT of refractoriness to platelet transfusions secondary to alloimmunization represents a
major clinical and research challenge in the field of platelet
transfusion therapy. Despite increased availability of HLA
type donors and a greater understanding of the factors that
influence the results of such transfusions, a large percentage
of allegedly histocompatible transfusions administered to alloimmunized patients are unsuccessfu~.’~3
In particular, it
may be difficult to provide long-term platelet transfusion
support for alloimmunized patients with unusual HLA types
for whom fewer perfectly matched donors are available. Although the number of potential donors increases when donors whose platelets are mismatched for HLA antigens are
considered, transfusions from such donors are often cited to
fail to produce satisfactory platelet count increment^.^ The
presence of lymphocytotoxic antibody (LCTAB) correlates
well with responsiveness to random donor platelet transfusions and serves as a good serologic screen for the diagnosis
of alloimm~nization.~.~
We therefore reviewed the results of
a large series of one antigen mismatched platelet transfusions
(OAMPT) to alloimmunized patients and assessed the relationship between lymphocytotoxic antibody levels in the recipient and the posttransfusion platelet count increments.
MATERIALS AND METHODS
We retrospectively analyzed the results of platelet transfusions
mismatched for a single HLA A or B antigen administered to consecutive patients refractory to random donor pooled platelet concentrate
transfusions. OAMPTs were used because that was the best available
product at the time. All data were from patients treated between
January 1976 and December 1989 at the University of Maryland
Cancer Center. OAMFTs were categorized according to whether the
donor’s mismatched antigen was serologically cross reactive with
any of the recipient’s HLA antigens, and to whether LCTAB was
present in the recipient.’
Patients were considered clinically stable if they had a temperature
lower than 101”F, no uncontrolled infection, severe hemorrhage,
palpable splenomegaly, or disseminated intra-vascular coagulation.'^*
None of the patients evaluated received any therapy or product that
might alter the transfusion results. Specificaly, no intravenous immunoglobulins, high dose steroids, leuckocyte-reduced platelet transfusions, or hematopoietic growth factors were administered. All transfusions were assessed by posttransfusion corrected count increments
(CCI) obtained 10 to 60 minutes after transfusion, where CCI equals
platelet count increment per microliter X body surface area (meter
Blood, Vol 87,No 9 (May 1). 1996:pp 3959-3962
RESULTS
Three hundred sixty-nine single donor transfusions that
were mismatched for a single HLA antigen were adminisFrom the University of Maryland Cancer Center, Baltimore, MD;
the Cleveland Clinic Cancer Center, Cleveland, OH: and the State
of Washington, Dept of Health, Seattle, WA.
Submitted June 7, 1995: accepted December 5, 1995.
This study was made possible in part by the generous support of
James Pastore, Sr.
Address reprint requests to Mohamad A. Hussein, MD, The Cleveland Clinic Foundation, 9500 Euclid Ave (T40), Cleveland, OH
441 95.
The publication costs of this article were defrayed in part by page
charge payment. This article must therefore be hereby marked
“advertisement” in accordance with 18 U.S.C. section 1734 solely to
indicate this fact.
0 1996 by The American Society of Hematology.
0006-4971/96/8709-0017$3.00/0
3959
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3960
HUSSEIN ET AL
Table 1. All OAMPTs to All Patients
LCTAB (%)
No. of transfusions
Mean CCI x IO3
Standard error
95% Confidence interval for mean CCI
% CCI 27,500
Regression coefficient (95% confidence interval)
P value of regression coefficient (t-test)
0-19
47
13.67
1.18
11.36-15.98
74.4
tered to 83 stable patients with acute leukemia. Transfusions
were divided into five groups according to the level of the
lymphocytotoxic antibody at the time of transfusion. The
results of all transfusions are analyzed in Table 1. Although
there was a statistically significant inverse relationship between the percentage of reactivity of the LCTAB and posttransfusion increments by regression analysis, the differences were most apparent in patients with more reactive
antibodies. Seventy-three percent of all OAMPTs to all patients with LCTAB <60% resulted in a successful platelet
increment with a mean CCI of 14,680. The CCI dropped
significantly (P value <.001) to a mean CCI of 9,800 in
transfusions to patients with LCTAB 260%. Furthermore,
in the least biased group of transfusions (Table 2) the percentage of successful transfusions dropped from 67% in patients with LCTAB <60% to 53% in recipients with LCTAB
2 6 0 % (P value .039).
Because we were somewhat surprised to see minimal effects of less reactive antibodies, we then attempted to correct
for the effects of a number of known donor selection factors
that could have modified these results. Repeated transfusions
from donors whose platelets produced good increments and
who donated repeatedly for the same patient (n = 80) were
then eliminated, so that only the first transfusion for each
donorhecipient pair was considered. Because transfusions of
platelets from donors with antigen mismatched for HLA B 12
and its splits (HLA B 44 and 45) produce satisfactory results
in approximately 70% of the incidents,” all mismatches for
this antigen and its splits were deleted (n = 34). To minimize
the influence of lymphocytotoxic antibody known to be reactive against the mismatched antigen such transfusions were
eliminated (n = 20). Finally, transfusions with platelets from
donors mismatched for antigens that are splits or strongly
cross-reactive with recipient antigens were eliminated (n =
24) to provide a group of 2 1 1 transfusions, including donor-
20-39
40-59
37
13.53
17.41
1.21
1.76
11.16-15.90
13.96-20.86
70.2
75.6
-1.34 (-0.74,-1.95)
1.001
47
60-79
75
10.80
0.85
9.13-12.47
69.3
80-1 00
163
9.43
0.67
8.12-10.74
53.9
recipient pairs that have been used only once, were not mismatched for HLA-B12 or its splits, were not mismatched for
any antigen splits or strong cross-reactive antigen groups,
and were given to patients without lymphocytotoxic antibody
against the mismatched antigen (Table 2).
The mean CCI and the percent of successful transfusions
were slightly lower in the more selected group of transfusions presented in Table 2 (13,970 and 7,780 in recipients
with LCTAB <60% and 260%, respectively) and notably
in patients with LCTAB >80%. Although the pattern of
results was similar. If only transfusions with CCI >7,500
are considered, the significant difference in the mean CCI
between the two levels of LCTAB is maintained (Table 3).
That is, even when transfusions were “successful” the average increment was lower in patients with higher LCTAB
levels.
When available, lymphocytotoxic antibody specificity
against mismatched antigens was evaluated. Antibody specificity was available for 202 of the transfusions. Antibody
against the mismatched antigen was detected in only 20
transfusions to 14 recipients. Ten of the twenty transfusions
to nine patients resulted in a successful increment (CCI
27,500) with six of the ten transfusions producing CCI
2 10,000.
DISCUSSION
There has been a striking increase in the use of platelet
transfusions in recent years, primarily as a consequence of
an increase in the number of patients with leukemia and other
cancers who are treated with more intensive and prolonged
chemotherapeutic approaches. Despite improvements in the
transfusion support of these thrombocytopenic patients, refractoriness to platelet transfusions remain a serious problem, thereby potentially limiting curative forms of therapy.
Although there are selection strategies that attempt to max-
Table 2. The Least Biased Grour, of Transfusions
LCTAB (%)
No. of Transfusions
Mean CCI x IO’
Standard error
95% Confidence interval for mean CCI
%CCI 27,500
Regression coefficient (95% confidence interval)
P value of rearession coefficient (t-test)
0-19
33
13.34
1.56
10.28-16.41
66.6
20-39
28
12.49
1.67
9.22-15.76
64.2
40-59
28
16.20
1.92
12.44-19.96
71.4
-1.56 (-0.79, -2.33)
<.001
60-79
38
1 1 .oo
1.21
8.63-13.37
71.0
80-100
84
7.74
0.85
6.07-9.41
45.2
Transfusions from donors used once, not mismatched for HLA 812 or its splits, no antibody against mismatched antigen, and no mismatches
for split or cross-reactive antigen.
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3961
ALLOIMMUNIZATION, ONE ANTIGEN MISMATCH, LCTAB
Table 3. Transfusions With CCI >7,500 in the Patients From Table 2
LCTAB (%)
No. of transfusions
Mean CCI x lo3
Standard error
95% Confidence interval for mean CCI
Regression Coefficient (95% confidence
interval)
Pvalue of regression coefficient (t-test)
0-19
22
18.03
1.51
15.07-20.99
imize the number of potential donors by using donors mismatched for cross-reactive antigens as described by Duquesnoy et al,’ and mismatching for HLA B12 and its splits by
Schiffer et al,13 there is a significant number of patients
who have few if any available donors. The use of donors
mismatched for one antigen could potentially expand the
donor pool.’
Our study reviewed a large number of OAMPTs to
LCTAB positive and negative patients. This group of patients was refractory to random donor pooled platelet concentrate. In contrast to older’ and more current report^'^ we
were surprised to find that 73% of all antigen mismatched
transfusions resulted in successful increments if the lymphocytotoxic antibody was <60% reactive. In recipients with
LCTAB 260%, 58% of all transfusions were still successful.
The mean CCI for successful transfusions to recipients with
LCTAB levels <60% was comparable with those noted following random donor platelet concentrate transfusions administered to stable patients and comparable with the success
of transfusions mismatched for HLA B12 and its split^.'^.'^
Duquesnoy et all analyzed the response of 29 patients to
transfusions mismatched for one or more HLA antigens and
demonstrated that 15 patients responded well to such transfusions on two or more occasions and that 14 patients consistently failed to respond. Unfortunately, the data of crossreactive and non-cross-reactive matched platelets were
pooled together. More recently, McFarland et al” evaluated
factors influencing the transfusion response to HLA matched
platelets in refractory patients and noted that in patients refractory to platelet transfusion with a LCTAB >20%, only
35% of OAMPT to all patients resulted in a successful recovery.
The unexpectedly high percentage of good responses in
our patient population is not related to donorh-ecipientbias
since the results were unchanged when only the first transfusion from a particular donor was considered. Moreover, the
high frequency of successful transfusions is not related to
using a particular antigen as a mismatch. Also, HLA B12
and its splits did not appear to account for these good results
because eliminating such transfusions did not affect the outcome. Some specificity of LCTAB could be demonstrated
in >50% of the transfusions and when possible, we attempted to select donors with mismatched antigens against
which the recipient did not demonstrate a specific antibody
(88% of all transfusions with LCTAB specificity available).
Nonetheless, 50% of the transfusions administered to patients with specific antibody against the mismatched antigen
were successful.
20-39
18
17.52
1.58
14.42-20.62
40-59
60-79
20
27
21.30
14.58
1.54
1.06
18.28-24.32
12.50-16.66
-0.95 (-0.10,-1.71)
80-100
38
15.11
0.84
13.46-16.76
.015
Platelet transfusions from donors selectively mismatched
for cross-reactive and certain non-cross-reactive HLA antigens were found to be more effective in HLA A2 negative
than in HLA A2 positive alloimmunized thrombocytopenic
patients.I6 Comparable with previous reports, 54% of our
patients were HLA A2 positive. The presence or absence of
the HLA A2 antigen in the recipients did not influence the
relationship between the LCTAB and the percentage of successful transfusions or the mean 10 minute or 1 hour CCI
(data not shown).
Our results further demonstrate that alloimmunization to
platelet transfusions is a complicated process with LCTAB
levels reflecting only one aspect of this immune reaction.”
LCTAB antibody levels can fluctuate over time in leukemia
patients and often can disappear despite continued transfusion.” Such fluctuations could account for occasional discrepant transfusion outcomes since antibody levels were not
always determined the same day as the transfusion. Nonetheless, such variations in antibody are unlikely to be a major
factor, since most antibody specimens were obtained within
2 weeks of the transfusion that was analyzed. Despite a
statistically significant inverse relationship between the level
of LCTAB and the response of OAMPT to alloimmunized
patients, 58% to 73% of recipients will have a satisfactory
platelet recovery posttransfusion.
Even though LCTAB levels did not discriminate between
successful versus unsuccessful responses to OAMPTs these
data support extending donor searches for alloimmunized
patients to include any single antigen mismatch, particularly
if the recipients’ LCTAB has lower reactivity. This strategy
will increase the donor pool and hopefully decrease the
search time for an appropriate donor.
REFERENCES
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transfusion of platelet “mismatched” for HLA antigens to alloimmunized thrombocytopenic patients. Am J Hematol 2:219, 1977
2. Lohrmann HP, Bull MI, Decter JA: Platelet transfusions from
HLA compatible unrelated donors to alloimmunized patients. Ann
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HUSSEIN ET AL
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From www.bloodjournal.org by guest on June 18, 2017. For personal use only.
1996 87: 3959-3962
The effect of lymphocytotoxic antibody reactivity on the results of
single antigen mismatched platelet transfusions to alloimmunized
patients
MA Hussein, EJ Lee, R Fletcher and CA Schiffer
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