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From www.bloodjournal.org by guest on June 17, 2017. For personal use only. Donor-Derived Red Blood Allogeneic Keith By Jill Hows, Beddow, Irena cases Six of donor-derived marrow immune hemolytic anemia antibodies after transplantation severe increased plasma rine to prevent that in each graft-v-host case, present positive antigens test was four (BMT) are intravascular hemolysis red cell transfusion, exchange. All recipients cases; disease. one to bone In 2/6 Investigations case; cases, showed ABO or Rho(D) red cell The direct antiglobulin serum antibody (anti-A, anti-D, one case) was first detected one to three weeks after BMT. Eluates made from recipient red cells showed the same specificity as serum antibody. Maximum hemolysis occurred nine to 1 6 days after BMT, suggesting that active production of antibody by “passenger” donor lymphocytes was the likely mechanism of hemolysis, rather than passive transfer of antibody A LLOGENEIC cytes humans to the bone involves recipient. marrow If this occurs, hemolysis. report six bone in to produce antibodies specific that are lacking on the donor’s it could hemolysis in the posttransplant cations such as renal failure severe We (BMT) the transfer of mature donor lymphoIt is theoretically possible for trans- ferred donor lymphocytes recipient red cell antigens red cells. transplantation present clinically for own as immune period. Conceivably, complicould occur in association with marrow transplantation (BMT) cases in which the appearance of red cell antibodies was associated with clinical and laboratory evidence of immune hemolysis. The peak time BMT, making marrow for hemolysis passive transfer infusion we suggest lymphocytes cause of hemolysis an unlikely that active stimulated the hemolysis. due to this analyzed 97 consecutive from one cyclosponine center and was one to two weeks of plasma antibody cause. From production by recipient To of the data determine mechanism, we the have cyclosporine-treated (Hammersmith). this phenomenon after in the presented, antibody by RBC antigens The was donor is the frequency of retrospectively BMT association strengthened patients between by our failure to find, on retrospective analysis, a single case of immune hemolysis or donor-derived antibody production in 1 3 patients treated with methotrexate in the postgraft period. MATERIALS AND and in the 1986: Spruce, D. Petz infusion. Retrospective analysis of 21 conBMT patients receiving marrow lacking ABO or D antigens present in the recipient showed that (1 ) 1 5/18 patients tested had red cell antibody production against recipient red cell antigens; (2) despite the frequent presence of antibody specific for recipient red cell antigens, only 3/21 patients developed clinically significant hemolysis; (3) clinical hemolysis could not be predicted by donor or recipient red cell antibody titers. We conclude that although red cell antibody against recipient antigens is frequently produced after minor ABO and D mismatched BMT in cyclosporine-treated recipients, marrow cyclosporine-treated only 1 0% immune likely to 1 5% cells. a 1986 of hemolysis. The of antibody source by Grune Rho(D) positive serum contained patients received cases develop clinically data presented show is “passenger” & Stratton, significant that the donor most lymphoid Inc. and the donor A Rho(D) negative; the donor’s weak anti-D at the time of the transplant. All cyclosponine after BMT to prevent graft-v-host disease (GVHD). Group 2. To assess the frequency of immune hemolysis, a retrospective analysis of 97 consecutive BMT patients transplanted at one center (Hammersmith) was carried out. All patients received cyclosporine in the postgraft period for the prevention of GVHD. Twenty-one patients received minor ABO or D mismatched marrow (ie, donor lacking ABO or Rh antigens present in the recipient) and were designated “group 2” patients. Within group 2, 14 patients received marrow from donors lacking recipient A or B antigens; this included cases 1 and 2 from group 1 . Seven D-positive recipients received marrow from D-negative donors and included case 6 from group 1 . Two patients were ABO and D mismatched. Group 2 patient charts were reviewed for evidence of immune hemolysis. Weekly blood bank records from the post-BMT period were searched for the occurrence of any positive direct antiglobulin tests (DAT). Sera from group 2 patients receiving minor ABO mismatched marrow, stored at - 20 #{176}C for up to 36 months, were tested for donor type IgG and 1gM anti-A and anti-B at one and three months after BMT. Serology Standard serological methods were used. The DAT was performed using polyspecific antihuman globulin (AHG) reagents. In DAT-positive cases, testing with anti-C3 and anti-IgG reagents was carried out. Eluates were made by the chloroform’ or ether2 technique. Anti-A and anti-B were estimated by titrating the stoned From 1 (January), Wayne After METHODS Group 1. Six patients from three transplant centers who presented clinically with immune hemolysis after BMT were investigated. Informed consent to investigations was obtained according to each of the transplant center’s ethical committee guidelines. Clinical and laboratory data are shown in Table 1 . Hematologic and biochemical data illustrating a typical case are shown in Fig 1. Patients 1 through 5 were transplanted from HLA-identical sibling donors and patient 6, from an HLA phenotypically matched unrelated donor. In cases 1 through 5, the donors lacked A on B antigens present on the recipients’ red cells. In case 6, the patient was A Vol 67, No Hemolysis R. Branch, Lawrence secutive Patients Blood, Donald A. Krance, attributed allogeneic reported. and Immune Transplantation Gordon-Smith, Robert was seen, 6/6 required and 1 /6 was treated by were receiving cyclospo- the donor lacked in the recipient. in 6/6. Relevant anti-B, Antibodies Marrow Edward Sniecinski, red cell Cell Bone pp 177-18 1 the Hospital, Duarte, Royal London; Calif and Supported CA 33572 Medical W12 © Health reprint 1 986 by the 18, Medical of by Public School, OHS City Childrens March Address the the awarded Submitted Postgraduate Hope Hospital. Service National 1985; requests Hammersmith School, San Grants Cancer accepted to Dr J.M. Hospital, Hammersmith National July Medical Center, Diego. No. CA 30206 and Institute. 18. 1985. Hows, Royal Du Cane Postgraduate Rd. London England. by Grune & Stratton, Inc. 0006-4971/86/6701-0027$03.00/0 177 From www.bloodjournal.org by guest on June 17, 2017. For personal use only. 178 HOWS Table 1 . Cli nical and La boratory Data-Patients Presenting With Group Case No. D,agnosis 1 D CGL R 1 7/M D 1 5/F Immunosuppressive A Therapy Pre-BMT R 0 + 1 Transfusions and Rh Type Age/Sex He molysis-Group Cy 60 - 60 TBI 200 Plate- RBC5 lets Post-BMT mg/kg DN Packed x 2 mg/m2 x 1 CyA A HDMP 0- A - . Details CGL 3 1 3/M SAA 1 1 /F 24/M 0 + 1 6/F A + 0 + B + Cv 60 Severe - IVH. mum 60 TBI 200 Cy 50 TNI x 2 mg/m2 x A + CyA 1 mg/kg 750 x 4 CyA 0 + B+ MP AML 1 1 /F 1 4/M 0 + A + 1 20 TBI VP-16 x 1 1 cGy 40 mg/kg x 1 CyA A + MP 0+ ALL 26/M 22/M B+ AB+ Cy 120 TBI mg/kg 1 20 x x 1 CyA 0+ 1 1 cGy MP B+ 6 SAA 32/F A 1 7/F A + - 50 Cy ALG mg/kg 1 2.5 x 4 mg/kg CyA x 4 HDMP A +9 Platelets total were nodal washed and irradiation; resuspended CyA, in AB cyclosporine; plasma. HDMP, D, donor; high-dose A + - Azathiaprine R, recipient; A sera against suitable test red cells. The agglutination titer at 20 #{176}C was measured as well as the titer at 37 #{176}C using anti-IgG AHG in the indirect antiglobulin test. Appropriate saline controls were performed. The lgG and 1gM components of the antibodies were estimated by testing the sera before and after treatment with 2-mercaptoethanol3 or dithiothreitol.4 The IgM titers were measured by agglutination at 20 #{176}C, and the lgG titers were estimated by the indirect antiglobulin test at 37 #{176}C. MP, DN, methylprednisone; (median, red cell 12) after antigens (median, 13) BMT. were after Group I. hemolysis Group between 1 patients days presented 9 and 10). The results of serological Table 2. The DAT first became mc Transfused (O+woshed) 2 2 1 $$$$$ 2 2 2 clinically 16 post-BMT (median, with antibodies case level day investigations are shown in positive at four to 22 days 3 $ were Six (including YS 20 POST 25 30 BMT Fig 1 . Case 3 from group 1 . Minor ABO mismatched BMT (donor 0 + , recipient B + ). Flow chart shows hematologic and biochemical evidence for hemolysis. Fourteen units of packed 0 + cells were required to maintain the hemoglobin between day 10 and day 1 9 post-BMT. Note that the hemoglobin. the lactic dehydrogenase. and the total bilirubin were normal for the first five days post-BMT. During the hemolytic episode. no incompatible isohemagglutinins were infused; RBCs transfused were washed group 0. platelets were group B or 0 washed and resuspended in fresh AB plasma. day required day to + maximum units RBCs day required day 16. TBI, total anti-lymphocyte body irradiation; globulin. cases 3 through 6 inclusive only transiently cases. present However, in the in the cases serological receiving I and 2 from to rise, data ABO group sera of the D-incompatible reaching is shown mismatched a in Table 3. marrow 1) developed a positive DAT after BMT. 1 ) showed clinical anti-A and anti-B However, only 2/6 (cases 1 and 2 in group evidence for immune hemolysis. Donor titers pre-BMT and recipient anti-A and anti-B and Three 15 hemolysis, 1 3. Five In titers one three cases by either and out D-incompatible donor of the seven marrow developed a.positive DAT-positive cases, BMT. In one case months 6 in group BMT hemolysis or recipient patients present. for IgG in group (including patient are could antibody antibody specific titers shown. not be or the The antibodies subclasses. 2 who 6 from received group I) DAT after BMT (Table 3). In all three anti-D was detected in the serum after (AG), anti-C and anti-E were also detected. Only one patient (AR) rhesus antibodies (AR) showed sis (case after clinical proportion of IgG and 1gM were not tested with antisera 10 maximum RBCs Antibodies against the recipient’s first detectable nine to I 5 days BMT. Group 2. Relevant out of 16 patients predicted 5 day required + 18. (case 6), the anti-D titer continued of 256 on day 70 after BMT. DAT-positive 0 maximum eluates prepared from recipient RBCs contained antibody to antigens present on recipient red cells of the same specificity found in the serum. Table 2 also shows that the red cell ABO-incompatible RESULTS to daunorubicin; ALG. units + 19 to + 14. 11 + Fourteen + 10 to RBCs hemolysis, Moderate - Cy, cyclophosphamide; methylprednisone; units + 1 2. Six units +9 TNI, Seven Moderate + day 1). + 10. B+ day hemolysis, day 5 day required + 10. required Moderate A + maximum Hemoglobinuria. day (seeFig 4 units + 10 to + 15. RBCs hemolysis. RBCs Treated Nine +22. Maximum #{149} day hemolysis. Severe 0+ Maxi+ 15. exchange. Six units + 16 to cGy day required + 16. x 5 cGy Hemoglobinuria. plasma Moderate A + HDMP and RBC Requirement hemolysis with x 5 cGy mg/kg DN of Hemolysis Transfusion RBCs 2 AL ABO Group and Rh Type of . ABO Immune ET with a positive clinical evidence I; see Tables I and DAT due to of hemoly- 2). DISCUSSION Anti-A residual and recipient anti-B plasma production cells against after major donor red ABO mismatched cells by From www.bloodjournal.org by guest on June 17, 2017. For personal use only. DONOR-DERIVED RBC ANTIBODIES Table 2. AND Serological Maximum No. Day Post-BMT Investig ation of Patients ABOGroup Hemolysis Case 179 BMT D A With I mmune sis-Group Hemoly 1 Day Post-BMT DAT Positive #{176} Presenting DAT First for Antibody Antibody in Eluate in Serum Day Post-BMT Serum Antibody Last Detected Positive 1 +15 0+ A- C3 +18 ND Anti-A +38 2 +16 0+ A+ C3 +15 ND Anti-A +24 3 + 10 0+ B+ lgG + C3 + 10 Anti-B Anti-B +42 4 + 10 0 + A + C3 + 4 Anti-A Anti-A + 30 5 + 12 B+ AB+ C3 +9 Anti-A Anti-A +42 6 + 13 A- A+ IgG + 13 Anti-D Anti-D +70t DAT, direct Serum antiglobulin antibody titer tAnti-D BMT not 256; is well test; D, donor; detectable later samples documented.5 R, recipient; in subsequent Hemolysis of donor the time of the transplant can of recipient antibodies by plasma removal of donor cells not done. not tested. cells at removal red ND, follow-up. from the red be prevented exchange6 marrow blood cally by or by with hemoglobinuria hemolysis occurring before infu- More recently, cases of immune recipients of minor ABO reported.9”#{176} Some reported Table 3. ABO Minor Antibody hemolysis occurring mismatched marrow episodes of hemolysis and Rhesus (D) Mismatch Recipient Antibody Titer 1 mo Post-BMT IgG/IgM Donor Antibody Ther IgG/lgM Relevant Patient BMT been clini- centers 2) nism. BMT, (Group Recipient Antibody Titer DAT Day Positive Post-BMT 3 mo Post-BMT IgG/lgM Anti-B 64/2 4/2 <2/<2 JC Anti-B 32/16 4/2 <2/.cz2 CW Anti-B 32/8 4/2 <2/<2 CR Anti-A 32/32 2/2 <2/<2 +4 AK Anti-A 32/64 8/2 <2/<2 + 22 64/128 <2/<2 <2/<2 + 28 0 +7 liver” two cases of acute renal failure were documented.9 in patients receiving and kidney’2 associated Cases minor transplants have of immune ABO mis- also appeared +8 Anti-B Anti-A 128/32 8/4 ND KS Anti-A ND ND ND 0 55 Anti-B ND ND ND 0 GB Anti-A 64/16 8/2 <2/<2 JW Anti-A 16/4 8/2 NW Anti-A 16/32 4/4 <2/<2 0 KR Anti-B 16/2 8/2 <2/<2 0 <2/’z2 0 +22t 0 19t SR Anti-A 16/8 2/<2 MTh Anti-A 64/64 4/4 4/<2 0 ND ND ND 0 Anti-D Anti-B JR Anti-D ARII Anti-D CJ Anti-D 0 AG Anti-D 0 Anti-Dil 4 256 +13t Anti-DIl Anti-Dl! Anti-Dil Anti-Dl! Anti-Cl! Anti-Cl! Anti-El! Anti-El! +22 Ant-D 0 0 0 0 Anti-D 0 0 0 0 Case 1 from §Minor ABO group and plasma transplant after minor our data, active production is the most likely mecha- hemolysis occurred one to three weeks after that passive transfer of antibody at the in blood products (Table cause. None of the ABO-incompatible 1); therefore, transfusion of incompatible plasma does not account for the phenomenon. Retrospective analysis of minor ABO mismatched BMT patients showed that only a minority (2/16) developed significant hemolysis, despite the production of occurs Table without signs of overt 3, it can be seen that cannot anti-B be predicted titers. Most from minor hemolysis. the onset From data shown in of immune hemolysis either donor or recipient anti-A or ABO mismatched patients were transfused with packed group 0 cells. However, the sion of group A or B red cells may have contributed severity of hemolytic group 1 (Table 1). episodes seen transfuto the I , 2, 4, and in patients 5 in We have shown that production of donor-derived antibody specific for recipient ABO antigens is transient, with the relevant antibody being virtually undetectable by three months post-BMT (Table 3). These data are consistent with after . by Buckner recipient BMT. et al6 in which ABO The . . antigens transient nature . donor-derived was absent or weak of donor-derived antibody one year antibody was rhesus (D) mismatch. No anti-D detected 1. detected Maximum suggesting three hemolysis. 1. #{182}Titer not estimated. last from hemolysis 1. ients. IlCase6fromgroup patients immune against recipient ABO antigens is not understood and contrasts with the more persistent donor-derived rhesus antibodies detected. Possible mechanisms are discussed below. The probable cause of immune hemolysis in case 6 group I not done. significant with time of the transplant is an unlikely patients in group 1 received significant against TP tClinically six presented ABO or D mismatch BMT. From of donor-derived red cell antibody a report +21 CH Case 2 from group investigated who antibody against recipient red cell antigens in the majority of cases (Table 3). Six out of 16 patients developed a positive DAT, suggesting that in vivo red cell sensitization often DD + have clinically PG 2/<2 We in have were AG Anti-D matched and in the literature. sion.7’t ND, severe, on day +98 (CJ) and +365 (AG). in recip- donor-derived . . anti-D. recipients serum until of 256 on day 70 after Anti-D. was not detectable in the 1 3 days after BMT and rose to a titer BMT. On retrospective analysis of 97 cases, seven D-positive patients received marrow from Dnegative donors. Three out of seven patients (including patient 6 in group 1) produced donor-derived anti-D (Table From www.bloodjournal.org by guest on June 17, 2017. For personal use only. HOWS 180 3). In contrast ABO to the cases, the tinued to produce year after BMT. antibodies tolerance lymphocytes antibody production of D-incompatible anti-D for prolonged The early disappearance in the marrow con- periods of up to one of donor-derived in the ABO cases may be due to high zone brought about by continued exposure of donor to A or B antigens in the recipients’ plasma and In tissues. contrast, the rhesus mismatched are only exposed to recipient lymphocytes transiently from the rhesus enough antibody BMT donor rhesus antigens until residual recipient red cells are circulation. The antigenic stimulus derived antibody to induce production. The transient recipients role of production tolerance, but cyclosponine in may instead facilitating be reported have pressed with observation. transplanted was used We have hemolysis of confirm is now retrospective by blocking to antigen proliferation case not of This prospectively agent to that of T lymphocytes However, T lymphocyte presensitized lymphocytes in production mismatched is a secondary case (AR), immune we have shown anti-D that the donor was presensitized to the D antigen, with present in the donor’s serum. The donor-derived anti-D produced a secondary in this immune recipient response was, to the therefore, D antigen the result of by the donor lymphocytes, analogous to anti-B in the ABO-incompatible the definite evidence gens in the other presensitization to rhesus antiin which donor-derived rhesus antibodies were was a I 5-year-old for donor two cases produced. boy who production of cases described. antibodies were detected (Ci), the by the patient’s sister. Her serum did rhesus antibodies at the time of the she I 7 years. has two rhesus It is therefore the frequency patients had anti-A and We have no Indeed, the donor for patient AG had not been transfused, suggest- D-positive possible evidence for children that during anti-D of clinical mismatched required the donor pregnancy and in the recipient hemolysis BMT, increased is low in it can be severe. red cell support, intravascular hemolysis, and one patient required plasma exchange. Renal failure was not apparent in our patients; however, this remains a potential It is not possible hemolyze from monitoring anti-B titers (Table 3). hemolysis receiving occurs minor to predict in approximately 10% ABO or D mismatched prevent exacerbation of hemolysis, mismatched transplants should or washed given. BMT group 0 red cells Platelet patients red to recipients be transfused cells. In D of the appropriate concentrates given should be recipient concentrated which patients donor and recipient Our data suggest that 0 platelets are used, transfusion patible plasma can be avoided in the presence ofcyclosporine.’6 In BMT, the donor lymphocytes are transfer to the recipient, so donor- cell antibody In one D minor the however, I 5 and complication. immunosup- immunosuppressive when transplant; two all so confirms this I 3 patients a single antibody. case, donor-derived rhesus marrow was donated not contain detectable D-negative proliferation is not impaired red studied or mitogens.’4”5 are reexposed to antigen minor ABO mismatched sensitized in vivo before derived response. being antiimmune in which Although observations. is a powerful primarily response recipients experience reviewed in this minor ABO and rhesus All six group 1 patients donor-derived been unable to identify due to donor-derived patients our Cyclosporine acts in transplant of donor-derived due to a primary In the third case strong in one center (Duarte) in whom methotrexate in the postgraft period to prevent GVHD (data shown). immune group been cyclosponine. Our own We have retrospectively that became sensitized to the D antigen that the production of donor-derived was a secondary response. to prolonged antibody production is uncertain. It is of interest that cases of immune hemolysis due to donor-derived antibody far production D, -C, and -E in the recipient was response by the donor lymphocytes. aged eliminated for donor- not leads ing ET AL will anti-A and significant 15% of cases transplants. To of minor ABO with packed mismatched ABO group cases, should be to minor ABO mismatched group or group 0. If group of significant by using platelet by centrifugation.’7 These ABO-incompreparations measures will, how- ever, not completely prevent hemolytic episodes. In summary, we have documented the occurrence of immune hemolysis in approximately 10% to 15% of marrow transplant recipients who received minor ABO or D mismatched marrow and were treated with cyclosporine. We believe antibody that hemolysis is due to active production of red cell by donor lymphoid cells in the early posttransplant period. sponine Antibody production immunosuppression. evaluate the syndrome. have minor role When of cyclosporine hemolysis suggested a transfusion mismatched transplants exacerbation may be associated with cycloFurther work is in progress to in the occurs, policy that pathogenesis it may for we be severe, of this and we patients receiving hope will prevent of the hemolysis. REFERENCES I . Branch DR, Sy Siok Hian AL, Petz LD: A new elution procedure using chloroform, a non-inflammable organic solvent. Vox Sang 42:46, 1982 2. Rubin H: Antibody elution from red blood cells. J Clin Pathol 16:70, 1963 3. Dacie JV, Lewis SM: Practical Haematology (ed 5). London, Churchill Livingstone, 1975 4. Olson PR, Weiblen BJ, O’Leary ii, Moscowitz 5, McCullough J: A simple technique for inactivation of 1gM antibodies using dithiothreitol. Vox Sang 30:149, 1976 5. Bussel A, Scheumetzler C, Gluckman E, Devengre A, Revion J: Major ABO incompatible bone marrow transplantation. Proceedings of Second European Symposium on Bone Marrow Transplantation. Amsterdam, Excerpta Medica, 1979, p 48 6. Buchner CD, Clift RA, Sanders JE, Williams B, Cray M, Storb R, Thomas ED: ABO incompatible marrow transplants. Transplantation 26:233, 1978 7. Blacklock HA, Prentice HG, Evans JP, Knight CBT, Gilmore Mi, Hazelhurst GRP, Ma DDA, Hoffbrand AV: ABO incompatible bone marrow transplantation: Removal of red blood cells from donor marrow avoiding recipient antibody depletion. Lancet 2:1061, 1982 8. Braine HG, Sesenbrenner LL, Wright 5K, Tutschka PJ, Saral R, Santos GW: Bone marrow transplantation with major ABO blood group incompatibility using erythrocyte depletion of marrow prior to infusion. Blood 60:420, 1982 9. Rowley 5, Braine H: Probable hemolysis following minor ABO incompatible marrow transplantation. Blood 60:613A, 1982 (suppl I) (abstr) From www.bloodjournal.org by guest on June 17, 2017. For personal use only. DONOR-DERIVED RBC ANTIBODIES AND BMT 10. Branch DR, Sniecinski I, Spruce W, Knance RA, Petz LD, St Jean J: Delayed immune hemolytic anemia following minor ABO mismatched bone marrow transplantation. Blood 64:755A, 1984 (suppl 1) (abstr) 1 I . Ramsey G, Nusbacher J, Stanzl TE, Lindsay GD: Isohemagglutinins of graft origin after ABO-unmatched liven transplantation. N Eng J Med 31 1:1 167, 1984 12. Mangal AK, Growe GH, Sinclair M, StilIwell GF, Reeve CE, Norman SC: Acquired hemolytic anemia due to “auto”-anti-A or “auto”-anti-B induced by Group 0 hemograft in renal transplant recipients. Transfusion 24:201, 1984 13. Mollison PL: Blood Transfusion in Clinical Medicine (ed 7). 1983, p 343 181 14. Andrus L, Lafferty KJ: cyclosponine A. Scand J Immunol Inhibition of T-cell I 5:449, 1982 activity by 15. Bunges D, Handt C, Rollinghoff M, Wagner H: Cyclosponine A mediates immunosuppression of primary cytotoxic T cell responses by impairing the release of interleukinI and interleukin-2. Eunilmmunol 11:657, 1981 16. Hess AD, Tutschska PJ, Santos GW: Effect of cyclosponine on the induction of cytotoxic T lymphocytes: Role of interleukinand interleukin-2. Transplant Proc I 5:2248, 1983 17. Widenman FK: Technical Manual (ed 8). Washington, American Association of Blood Banks, 1981, p 407 DC, 1 From www.bloodjournal.org by guest on June 17, 2017. For personal use only. 1986 67: 177-181 Donor-derived red blood cell antibodies and immune hemolysis after allogeneic bone marrow transplantation J Hows, K Beddow, E Gordon-Smith, DR Branch, W Spruce, I Sniecinski, RA Krance and LD Petz Updated information and services can be found at: http://www.bloodjournal.org/content/67/1/177.full.html Articles on similar topics can be found in the following Blood collections Information about reproducing this article in parts or in its entirety may be found online at: http://www.bloodjournal.org/site/misc/rights.xhtml#repub_requests Information about ordering reprints may be found online at: http://www.bloodjournal.org/site/misc/rights.xhtml#reprints Information about subscriptions and ASH membership may be found online at: http://www.bloodjournal.org/site/subscriptions/index.xhtml Blood (print ISSN 0006-4971, online ISSN 1528-0020), is published weekly by the American Society of Hematology, 2021 L St, NW, Suite 900, Washington DC 20036. 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