Alloimmunization against human platelet antigen 2 (HPA2) in a series of multitransfused β-thalassemia patients

Abstract

In our study we investigated the presence of anti-human platelet antigen (HPA) alloantibodies in a series of 10 beta-thalassemia major patients submitted for more than 10 years to periodic blood transfusions (every 2-3 weeks). We found that 2 out of the 10 patients developed anti-HPA2a + HPA1b and anti-HPA2b antibodies. Our results highlight that HPA alloimmunization in multitransfused patients is a real possibility.

Full text

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Alloimmunization against human platelet
antigen 2 (HPA2) in a series of multi-
transfused
bb
-thalassemia patients
PI
ER
LU
IGI
TA
ZZARI
, FR
ANCESCA
RI
CCI
, CR
ISTINA
TA
SSI
,
A
N
DREA
BO
NTADINI
, FI
ORENZA
FR
UET
, RO
BERTO
CO
NTE
Servizio di Immunoematologia e Trasfusionale, Policlinico
S. Orsola-Malpighi, Bologna, Italy
In our study we investigated the presence of anti-
human platelet antigen (HPA) alloantibodies in a
series of 10
b
b
-thalassemia
major
patients submitted
for more than 10 years to periodic blood transfusions
(every 2-3 weeks). We found that 2 out of the 10
patients developed anti-HPA2a+HPA1b and anti-
HPA2b antibodies. Our results highlight that HPA
alloimmunization in multitransfused patients is a real
possibility.
Patients affected by b-thalassemia major are usual-
ly submitted to many transfusions of packed red
blood cells during their life. Multitransfused patients
are exposed to different immunogens due to the pres-
ence of leukocytes and platelets in packed red blood
cells.
1,2
Antibodies raised against the latter compo-
nents are responsible for some of the febrile non-
hemolytic transfusions reactions (FNHTR) and fil-
tered packed red cells are then needed to avoid this
kind of reactions. Little is known about possible
alloimmunization against human platelets antigens
(HPA); this is more difficult to study and to charac-
terize than HLA alloimmunization.
3,4
In this context
we analyzed our series of b-thalassemia patients to
find alloimmunization against red blood cells, leuko-
cyte and platelets.
Ten patients affected by b-thalassemia major (clin-
ical characteristics summarized in Table 1) were sub-
mitted to periodic tests for the presence of alloanti-
bodies. Tests were also performed in the case of
transfusion reactions.
Antibodies against red cell antigens were detected
by standard indirect tests using rabbit anti-human
immunoglobulin antisera. Antibodies against HLA
were analyzed by a standard cytotoxicity test on HLA-
typed donors.
The search for alloantibodies against HPA was per-
formed by a standard indirect immunofluorescence
test on random and HPA-typed donor platelets.
5
The
samples were also run on a monoclonal antibody-
immobilized platelet antigen (MAIPA) test
6
to define
the specificity of the recognized antigen. Patients
found positive for anti-HPA antibodies were geno-
typed for HPA-1,-2-,3,-5 genes with SSP-PCR.
Clinical records (Table 1) showed that 6 patients
h
ad suffered from FNHTR, indicating a possible
alloimmunization against platelets and/or leuko-
cytes. Two patients showed alloimmunization against
red blood cell (one anti-Kell and the other anti-Kp
a
),
while 5 out of 10 had HLA antibodies with a very
wide specificity (>80% of positive donors). One
patient (#4) had anti- HLA-B35+51 antibodies.
Concerning HPA alloantibodies, patient #1 had
HPA2b alloantibodies and patient #2 HPA2a+HPA1b
alloantibodies. It should be underlined that HLA anti-
bodies with wide reactivity were found in sera from
both patients, and patient #1 had also anti-Kell anti-
bodies.
HPA gene typing showed that patient n.1 (anti-
HPA2b) was HPA1a/a, HPA2a/a, HPA3b/b, HPA5a/b.
Patient #2 (anti-HPA2a) showed the following typing:
HPA1a/a, HPA2b/b, HPA3a/a, HPA5a/a.
We analyzed sera from 10 multitransfused patients
suffering from b-thalassemia major, looking for both
HLA and HPA specificities. HLA antibodies were
found in 6 out of the 10 patients. Our investigation
also showed that HPA alloimmunization is a real pos-
sibility since two patients developed HPA antibodies
(anti HPA2b and anti HPA2a+HPA1b).
In multitranfused patients alloimmunization is usu-
ally regarded as strictly related to the presence of HLA
alloantibodies, since these are responsible for most
of the FNHTRs. In addition HPA alloantibodies may
be implicated. A retrospective analysis showed that
patient #2 also suffered from FNHTR also when
receiving blood from HLA-matched donors, positive
for the HPA2a antigen. These results suggest that
HPA may have been responsible for the FNHTRs.
765
Scientific letters
Table 1. Characteristics of
bb
-thalassemia patients.
N. Pts. Age/Sex No. of transfused RBC units Transfusion
(non-filtered (filtered reactions
U until U beginning
1990) from 1991)
1
C.M. 26/M 464 215 chills-hyperthermia
2
C.A.
24/F
568
160
chills-hyperthermia
3 D.F.M. 34/F 760 212 chills-hyperthermia
4 D.L 21/F 423 202 chills-hyperthermia
5
F.L
31/M
804
240 chills-hyperthermia
6 F.A. 23/F 420 184 none
7 F.M. 19/M 260 162 none
8
I.I.
27/F
740
187 chills-hyperthermia
9 R.A. 21/F 324 164 none
10 S.F 26/M 580 215 none
M= male; F=female; U=units.
©Ferrata Storti Foundation

766
A few considerations should be highlighted: (i) in
c
hronically multitransfused patients, HPA alloanti-
bodies might be responsible for some of the FNHTRs;
(ii) in our series rare HPA specificities were found,
involving the HPA2 alloantigens. In this context, it
could be hypothesized that the mechanisms of recog-
nition in multitransfused patients might be different:
alloantigens expressed on the CD42 protein (HPA2)
might be more immunogenic in multitransfused
patients than alloantigens expressed in the CD41/61
complex (HPA1 or HPA3) or in the CD49b-related
antigen (HPA5), which are more frequently involved
in neonatal alloimmune thrombocytopenia or in
post-transfusional purpura.
7-10
Key words
Alloimmunization,
b
-thalassemia, human platelet antigen
(HPA), multitransfused patients
Correspondence
Roberto Conte, MD, Servizio di Immunoematologia e
Trasfusionale, Policlinico S.Orsola-Malpighi, via Massaren-
ti 9, 40138 Bologna, Italy.
Phone: international +39-051-6364779 • fax: interna-
tional +39-051-6363527 • E-mail: trasfusionale@orsola-
malpighi.med.unibo.it
References
1. Sirchia G, Zanella A, Parravicini A, Morelati F, Rebul-
la P, Masera G. Red cell alloantibodies in Thalassemia
major. Results of an Italian cooperative study. Trans-
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2. Rosse WF, Gallaghen D, Kinney TR, et al. Transfusion
and alloimmunization in Sickle Cell Disease. Blood
1990; 76:1431-7.
3. Kickler T, Kennedy SD, Braine HG. Alloimmunization
to platelet-specific antigens on glycoprotein IIb/IIIa
and Ib/IX in multiply transfused thrombocytopenic
patients. Transfusion 1990; 30:622-5.
4. Blanchette VS, Chen L, De Friedberg ZS, Hogan VA,
Trudel E, Decary F. Alloimmunization to PLA1 platelet
antigen: results of a prospective study. Br J Haematol
1990; 74:209-15.
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transfusion in a patient affected by Glanzmann’s
thromboasthenia with antibodies against gpIIb-IIIa.
Haematologica 1997; 82:73-4.
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Monoclonal antibody-specific immobilization of
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1722-6.
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alloimmunization against fetal platelet antigens: A
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Mueller-Eckhardt C. Post-transfusion purpura. Br J
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von dem Borne AEGKr, von Riesz, Verhengt F. Bak
a
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Spontaneous decrease of spleen size in a
patient with type 1 Gaucher’s disease
ME
IR
DJ
ALDETTI
,* RA
CHEL
ST
RAUSSBERG
,° HA
NNA
BE
SSLER
,*
A
R
I
ZI
MRAN
,
#
AM
OS
M. CO
HEN
@
*Laboratory for Hematology Research, Rabin Medical Center-
Golda Campus, Petah-Tiqva; °Department of Pediatrics "C",
S
chneider Children Medical Center of Israel;
#
G
aucher Clinic,
Shaarei-Zedek Medical Center, Jerusalem;
@
Hematology Unit,
R
abin Medical Center-Golda Campus, Petah-Tiqva and the
Sackler School of Medicine Tel-Aviv University, Tel- Aviv, Israel
We present a patient with type 1 Gaucher’s disease in
whom the spleen size during 34 years of follow-up
reached a maximum of 6 cm. below the costal margin,
but in 1993 began to decrease spontaneously and
presently can no longer be felt by abdominal palpation.
Gaucher’s disease is an autosomal, recessive stor-
age disease due to glucocerebrosidase deficiency; the
spleen may increase to ten times the normal size.
1
We
have treated more than 30 patients with this condi-
tion, but the patient presented here is the only one in
our series in whom a spontaneous regression of the
spleen size was noted.
A.M. is a 62-year-old nurse of Ashkenazi origin, a
mother of two sons. In 1959, when she was 37 year-old,
she was diagnosed as having Gaucher’s disease follow-
ing the appearance of mild purpura, petechiae and
hepatosplenomegaly of 2 and 4 cm. below the costal
margins. Blood examinations showed: hemoglobin
12.2 g/dL, white blood cells 4.7
310
9
/L and platelets
330310
9
/L. Serum acid phosphatase 5.5 U (normal
range 0-0.8 U). Bone marrow aspiration biopsy
revealed Gaucher’s cells. X-ray examination was remark-
able for Erlenmeyer flask deformity of the femora.
One son is a heterozygous carrier of the disease.
During the years of follow-up the size of the spleen
progressively increased, reaching a maximum of 6 cm.
below the costal margin. Bone biopsies performed in
1966 and 1973 showed the presence of Gaucher’s
cells. However, beginning in 1993, the size of the spleen
progressively decreased by about one cm per year until
1996, when the spleen could be not palpated at all.
Two abdominal ultrasounds and a
99
Technetium sul-
fur colloidal scan, showed a spleen size of 10 cm. A
Doppler examination of the spleen vessels was with
-
out pathological fi
ndings. Examination of her periph
-
eral white blood cells showed that she is a homozy-
gote for the 1226 G variant of Gaucher’s disease.
The onset of the disease, the clinical and laborato-
ry findings and the family history of the patient are
consistent with the diagnosis of adult, type 1
Gaucher’s disease. The long course and almost asymp
-
tomatic presentation of the illness, exclude the possi-
bility of myeloproliferative disorders in which pseudo-
Gaucher’s cells may be found. Our patient should be
distinguished from those with asplenomegalic (cryp-
Scientific letters
©Ferrata Storti Foundation