Red blood cell alloimmunization in transfusion-dependent Egyptian patients with thalassemia in a limited donor exposure program

BACKGROUND: Thalassemia is considered the most common hemoglobinopathy in Egypt and is one of its major health problems. Lifelong red blood cell (RBC) transfusion remains the main treatment for severe forms; however, RBC alloimmunization results as a complication of regular transfusions due to repeated exposure to foreign antigens. The objective was to compare the frequency of alloantibodies in a group of patients in a limited donor exposure program (LDEP) with those receiving RBCs from multiple donors in Egyptian transfusion‐dependent patients with thalassemia. STUDY DESIGN AND METHODS: A total of 235 regularly transfused patients with thalassemia were studied, 36 of which were on LDEP. All patients were investigated for the presence of RBC autoantibodies and alloantibodies, followed by antibody identification for positive patients. RESULTS: Forty‐six (19.5%) patients developed RBC alloantibodies. The most common clinically significant alloantibodies were directed against antigens in the Kell and Rh systems. Development of alloantibodies was associated with older age, higher transfusion frequency, and splenectomy. A trend toward lower alloimmunization was elicited in the LDEP group, where 8.3% (3/36) patients were alloimmunized compared to 21.6% (43/199) in the non‐LDEP one (p = 0.057). CONCLUSIONS: Examination of donor RBCs for presence of Kell and Rh(E) antigens before transfusion can help decrease RBC alloimmunization. Further larger studies are required to assess the frequency of alloantibody production in patients on LDEP.     

ABO mismatch may affect engraftment in multiple myeloma patients receiving nonmyeloablative conditioning

BACKGROUND: Blood group incompatibility does not appear to affect the overall outcome in patients undergoing myeloablative conditioning before allogeneic BMT. Data on ABO-mismatched transplantation in the nonmyeloablative setting are limited. STUDY DESIGN AND METHODS: A retrospective analysis of the effects of ABO mismatches in multiple myeloma patients who received a nonmyeloablative conditioning regimen was conducted. RESULTS: Three of 27 patients received a minor ABO-mismatched graft, all with evidence of hemolysis before converting to donor ABO group on Days 10, 15, and 6. Six patients received a major ABO-mismatched graft; of these, three developed GVHD of more than grade 2 and subsequently converted to the ABO blood group of the donor on Days 38, 33, and 43. Of the three patients without GVHD, one rejected the allograft and had autologous reconstitution. One remained a mixed chimera to Day 100 despite three donor lymphocyte infusions, and one developed pure RBC aplasia. None of the ABO-matched patients rejected the graft, whether they developed GVHD or not. RBC transfusions were significantly higher in the major and minor ABO-mismatched patients than in the ABO-matched patients, with medians of 12 units (range, 2-35), 13 units (range, 5-18), and 4 units (range, 2-15), respectively (p = 0.02). ABO-matched patients had a similar incidence of GVHD, with 5 of 9 ABO-mismatched patients (56%) having more than grade 2 versus 10 of 18 (56%). Four of 9 ABO-mismatched patients (44%) were mixed chimeras up to Day 100 versus 2 of 18 ABO-matched patients (11%), and the difference was significant (p = 0.01). CONCLUSION: Patients with ABO mismatch had problems with engraftment, including graft rejection, pure RBC aplasia, and mixed-lineage chimerism. RBC transfusions were significantly higher in the ABO-mismatched recipients. GVHD may play a role in engraftment, possibly by facilitating the disappearance of native ABO antibodies via graft-versus-plasma cell effect. A prospective study to evaluate the effects of ABO mismatch on engraftment in the nonmyeloablative setting is needed.     

主要ABO血型不合异基因造血干细胞移植后纯红细胞再生障碍

20例主要ABO血型不合异基因造血干细胞移植（allo-HSCT)患中，6例发生纯红细胞再生障碍（PRCA）。PRCA对中性粒细胞和血小板植入以及Ⅱ-Ⅳ度aGVHD并无影响。6例PRCA患血型均为O型，而供血型5例为A型，1例B型，提示供／受血型A／O是主要ABO血型不合allo-HSCT后PRCA发生的高危因素。4例除给予RBC输注无其它特殊治疗，随着凝集素滴度降至＜8，红系造血自然恢复，而另2例尽管给予重组人红细胞生成素（rhEPO）治疗红系再障仍持续＞300天，经供型血浆置换而红系恢复造血。在本组病例，环孢菌素在PRCA发生中并无作用，而GVHD发生则可促进红系造血恢复。     

Transfusion policy: when to stop the use of extremely rare blood for an allogeneic hematopoietic progenitor cell transplant recipient with a history of red cell alloimmunization

BACKGROUND: Decisions for when to select, and when to discontinue, antigen-negative blood in hematopoietic progenitor cell transplantation (HPCT) recipients with red blood cell (RBC) antibodies can be confusing. In HPCT performed for sickle cell anemia patients who require extremely rare antigen-negative blood, the balance of caution and practicality is further complicated. CASE REPORTS: Four sickle cell anemia patients with current or historic RBC antibodies underwent allogeneic HPC transplantation. One required extremely rare (group O D-, hr(B)-) blood. None of the antibodies caused significant hemolysis after transplant. In the case requiring rare blood, antigen-negative blood was requested after donor RBC engraftment because of incomplete donor white blood cell (WBC) chimerism. CONCLUSIONS: RBC antibodies derived from a recipient of allogeneic HPCT rarely cause significant hemolysis, in contrast to the more severe picture sometimes seen with donor-derived antibodies. When donor WBC chimerism is delayed past the time of donor RBC engraftment, there can be concern for the possibility of future recipient-type antibody production. Even 100 percent donor lymphocyte chimerism is no guarantee of total host plasma cell ablation. Immunoglobulin allotyping, when informative, can suggest chimerism for several years. Recipient-type blood, when extremely rare, may not be available for that duration.     

Safety and impact of donor-type red blood cell transfusion before allogeneic peripheral blood progenitor cell transplantation with major ABO mismatch

BACKGROUND: Changes within the ABO system are regularly observed phenomena in allogeneic bone marrow transplantation (BMT) and peripheral blood progenitor cell transplantation (PBPCT). Major ABO mismatch can lead to different clinical problems including acute hemolysis after infusion of the allograft, delay of red blood cell (RBC) engraftment, or even manifestation of pure red cell aplasia (PRCA). STUDY DESIGN AND METHODS: This retrospective study demonstrates the safety and the impact of donor-type RBC transfusion before allogeneic PBPCT in major ABO settings as routinely performed at our transplantation unit. This study reports on transfusion of mismatched RBCs at the end of the conditioning period in 35 patients who underwent allogeneic PBPCT, which led to a decrease in isoagglutinin titers in most cases. RESULTS: A decrease of isoagglutinin titer after donor-type RBC transfusion can significantly reduce the demand of RBC transfusion between transplantation and Day +30 (p = 0.003). Interestingly, patients who developed PRCA were not observed, a complication being regularly documented by other groups. CONCLUSION: A decrease of isoagglutinin titers by in vivo immunoadsorption before allogeneic PBPCT does not only lack severe complication but also leads to a reduction in demand of RBC transfusion after engraftment and may reduce the incidence of PRCA in these patients.     

Impact of ABO incompatibility on allogeneic peripheral blood progenitor cell transplantation after reduced intensity conditioning

BACKGROUND: Most studies indicate that ABO incompatibility has no effect on the clinical outcome after allogeneic peripheral blood progenitor cell (PBPC) transplantation (allo-PBPCT). However, it carries additional risks of hemolytic reactions, delayed red blood cell (RBC) engraftment, and pure red cell aplasia (PRCA). Data on these events after reduced intensity conditioning (RIC) regimens are limited, but recent studies have suggested a higher transplant-related mortality (TRM) and morbidity in this setting. STUDY DESIGN AND METHODS: We investigated the impact of ABO-matching on the outcome of 77 patients included in a prospective RIC allo-PBPCT protocol, focusing on engraftment, transfusion requirements, graft-versus-host disease, TRM, and survival. RESULTS: There were 17 (22%) minor and 8 (10%) major ABO-incompatible transplants. No graft failures were observed. After major ABO-incompatible grafts, RBC engraftment was delayed, longer thrombocytopenia periods were documented, and transfusion requirements increased. A transient mild hemolysis occurred in 10 patients, 7 (41%) minor and 3 (37%) major ABO-mismatched. A PRCA was observed in a O+ patient with a pretransplant anti-Jka, grafted from an A + Jka+ donor. Graft-versus-host disease, disease progression, and TRM were not affected by ABO matching. CONCLUSION: ABO incompatibility was not associated with clinically relevant hemolysis after the RIC protocol used and did not impair the clinical outcome. PRCA was only observed in one patient, with a non-ABO RBC allo-antibody.     

Relationship of CD34+ cells infused and red blood cell transfusion requirements after autologous peripheral blood stem cell transplants: a novel method of analysis

BACKGROUND: CD34+ cells infused predicts myeloid and platelet engraftment at the time of autologous stem cell transplantation. An association between the number of CD34+ cells infused and erythroid engraftment has yet to be established. STUDY DESIGN AND METHODS: Red blood cells transfused after autologous transplantation were compared with the number of CD34+ cells infused. Myeloid engraftment was assessed to confirm that normal engraftment kinetics occurred. RESULTS: Logistic regression established that the logarithm of the number of CD34+ cells infused (p = 0.0498) and admission hemoglobin (Hb; p < 0.001) predicted the need for transfusion. In those patients who required transfusion, standard regression methods were not valid. A novel model demonstrated that the initial Hb (p < 0.001) and diagnosis (p = 0.047) were significant predictors of transfusion requirements in patients needing transfusion. However, the number of CD34+ cells infused did not predict transfusion requirements in this group (p = 0.226). As myeloid engraftment demonstrated kinetics that have been previously described, it can be inferred that erythroid engraftment was not atypical. CONCLUSION: The number of CD34+ cells infused predicted the need for transfusion, although it did not predict the number of RBCs transfused in those patients having transfusion during their admission for autologous stem cell transplant.     

Regeneration of erythropoiesis after related- and unrelated-donor BMT or peripheral blood HPC transplantation: a major ABO mismatch means problems

BACKGROUND: Blood group incompatibility in allogeneic BMT is common but does not appear to affect the outcome in terms of incidence of graft rejection or delayed engraftment. However, major ABO incompatibility may be associated with prolonged erythroid aplasia. STUDY DESIGN AND METHODS: In a retrospective analysis of 286 allogeneic transplant recipients, the prevalence of prolonged erythroid aplasia, including pure RBC aplasia, was determined. RESULTS: Patients receiving major ABO-incompatible grafts showed a significant delay in reticulocyte engraftment (median, 32 days; range, 12-347) from that in patients receiving ABO-identical (20; 10-152) or minor ABO-incompatible (21; 12-47) grafts. Pure RBC aplasia occurred in 7 (3%) of 240 evaluable recipients and was observed only in the major ABO-incompatible group (7/43, 16%). Treatment of pure RBC aplasia consisted of either plasma exchange, which resulted in a response within 16 to 68 days, or immunoadsorption, in which the response occurred between Days 119 and 204 after initiation of treatment. CONCLUSION: Major ABO incompatibility may lead to delayed reticulocyte engraftment, resulting in prolonged transfusion dependency and increased risks of transmission of infection and iron overload. Therefore, therapeutic strategies should be taken into consideration to allow erythroid reconstitution in these patients.     

Outcomes after major or bidirectional ABO-mismatched allogeneic hematopoietic progenitor cell transplantation after pretransplant isoagglutinin reduction with donor-type secretor plasma with or without plasma exchange

BACKGROUND: Major ABO mismatch in hematopoietic progenitor cell transplantation (HPCT) is associated with a range of immunohematologic consequences including progenitor cell infusion (PCI)‐related hemolysis, delayed red blood cell engraftment, and pure red cell aplasia (PRCA). Although pretransplant (recipient) isoagglutinin reduction may be associated with decreased immunohematologic complications in this setting, there is no consensus with respect to strategies for isoagglutinin reduction. STUDY DESIGN AND METHODS: This observational study assessed the efficacy of a standardized pretransplant isoagglutinin reduction strategy incorporating donor‐type secretor plasma infusions with or without plasma exchange to prevent PCI‐associated hemolysis and PRCA in major or bidirectional ABO‐mismatched peripheral blood HPCT. All major or bidirectional ABO‐mismatched HPCTs performed between 1999 and 2010 were identified from an institutional database. Immunohematologic outcomes were determined retrospectively by review of individual medical records. RESULTS: In total 110 major or bidirectional ABO‐mismatched HPCTs had been performed. No patient developed hemolysis after PCI. With respect to PRCA incidence, 16 patients (15%) were excluded due to early mortality and three (3%) due to incomplete data; of the remaining 91 patients, five (5%) developed PRCA. Patients with PRCA had significantly higher pretransplant isoagglutinin titers (p = 0.0001) compared to those who did not develop PRCA. CONCLUSIONS: Use of a standardized pretransplant isoagglutinin reduction strategy including donor‐type secretor plasma infusions is both safe and efficient in preventing PCI‐associated hemolysis and is associated with low rates of posttransplant PRCA.     

TRANSPLANTATION AND CELLULAR ENGINEERING: Prolonged isolated red blood cell transfusion requirement after allogeneic blood stem cell transplantation: identification of patients at risk

BACKGROUND: Delayed donor red blood cell chimerism (DRCC), pure red blood cell aplasia (PRCA), and autoimmune hemolytic anemia (AIHA) are poorly documented complications after hematopoietic cell transplantation (HCT). The clinical variable “prolonged isolated red blood cell transfusion requirement” (PRTR) was evaluated as a trigger for an extended diagnostic workup. STUDY DESIGN AND METHODS: PRTR was defined as the need for red blood cell (RBC) transfusions beyond Day 60 after HCT. We analyzed 487 patients transplanted between 2000 and 2006. Median age was 37 years (range, 0‐70 years). Peripheral blood stem cells (n = 344), marrow (n = 138), and cord blood (n = 5) from 278 unrelated and 209 family donors were used. RESULTS: Univariate analysis identified age (incidence of 18.3% among elderly patients, 10.5% in adults, and 2.0% among children [p = 0.002]), ABO incompatibility (16.4% after major incompatible, 2.9% after minor incompatible, and 9.4% after ABO‐compatible transplantations [p = 0.003]), conditioning (15.2% after reduced‐intensity regimens vs. 7.3% after myeloablative conditioning; p = 0.006), donor type (13.2% after HLA‐matched unrelated, 13.6% after mismatched unrelated, 5.7% after matched related, and 0.0% after mismatched related grafts; p = 0.026), and acute graft‐versus‐host disease (aGVHD; 7.1% with aGVHD vs. 12.5% without aGVHD; p = 0.046) as predisposing factors. In multivariate analysis minor ABO incompatibility (odds ratio [OR] = 0.2, p = 0.01), younger age (OR = 0.1, p = 0.02), and matched related HCT (OR = 0.4, p = 0.02) remained independent protective factors. CONCLUSIONS: PRTR could serve as a trigger for a standardized screening for DRCC, PRCA, and AIHA after HCT.     

ABO血型主要不合供者外周血干细胞单采中COM.TEC血细胞分离机的应用

背景：异基因外周血造血干细胞移植大约1/3是在ABO血型不合的供受者之间进行的。目的：探讨ABO血型主要不合供者外周血造血干细胞在不去除红细胞情况下应用COM.TEC血细胞分离机直接回输给受者的可行性。方法：27例HLA全相合同胞供者皮下注射粒细胞集落刺激因子5μg/（kg.d）,连续5d干细胞动员,于第5天开始应用COM.TEC血细胞分离机进行外周血造血干细胞单采,每次总处理血量为3.0～3.5个供者全身血量。ABO相合供者按常规方法进行单采,主要不合供者采取动态调整白膜收集量和保持稳定充足的血流量以减少红细胞污染。结果与结论：27例供者中ABO主要不合供者11例,相合供者16例。主要不合组产品体积及红细胞内含量均显著低于相合组（P〈0.05）,回输给受者均未出现急性溶血反应;2组单个核细胞及CD34＋细胞计数差异无显著性意义（P〉0.05）,受者均获造血重建,中性粒细胞及血小板重建时间相似（P〉0.05）。提示应用COM.TEC血细胞分离机进行ABO主要不合供者外周血造血干细胞单采,可以保持稳定充足的血流量情况下通过动态调整白膜收集量参数,在不影响采集产品产量和质量的同时显著减少红细胞的污染,预防回输后受者的急性溶血反应。     

ABO mismatch increases transplant-related morbidity and mortality in patients given nonmyeloablative allogeneic HPC transplantation

BACKGROUND: ABO mismatch has not been thought to affect the outcome of patients undergoing myeloablative conditioning and allogeneic HPC transplantation. Data on transplant-related complications after ABO-mismatched transplantation after nonmyeloablative conditioning are limited. STUDY DESIGN AND METHODS: Therefore, 40 patients were analyzed after nonmyeloablative conditioning with regard to ABO compatibility. Eleven received a minor and bidirectional and 8 a major ABO-mismatched graft. RESULTS: Four patients had evidence of hemolysis during engraftment, being lethal in one, and three developed pure RBC aplasia. Six patients in the ABO-mismatched group developed thrombotic microangiopathy, and three of them died. ABO-identical and ABO-mismatched patients had a similar incidence of GVHD. Viral infections occurred in both groups in equal shares. Patients with an ABO-mismatch had to be rehospitalized until Day 100 for a median of 19 days versus 0 days in the identical group (p < 0.05). Overall survival was 60 and 57 percent in the ABO-identical and ABO-mismatch groups, respectively. The probability of transplant-related mortality was 0 versus 28 percent in the identical group compared to patients with an ABO mismatch (p < 0.05). The probability of relapse or progression was 76 versus 25 percent in the ABO-identical group compared to the ABO-mismatched group, respectively. CONCLUSION: Significantly more patients with ABO mismatch showed transplant-associated complications and died as a result of transplant-related causes.     

Prophylactic red blood cell exchange for prevention of severe immune hemolysis in minor ABO-mismatched allogeneic peripheral blood progenitor cell transplantation after reduced-intensity conditioning

BACKGROUND: Delayed severe immune hemolysis due to donor-derived passenger lymphocytes is observed in minor and/or bidirectional ABO-mismatched transplants, especially after reduced-intensity conditioning (RIC). The incidence is reported in up to 30 percent of patients and can result in multiorgan failure (MOF) and death. STUDY DESIGN AND METHODS: A first group of 32 patients (historical control) underwent RIC followed by allogeneic hematopoietic peripheral blood progenitor cell transplantation at our institution. In 5 of 10 patients with a minor and/or bidirectional ABO-mismatched graft, severe immune hemolysis was observed, leading to death in 3 of them. Therefore, we initiated a protocol with prophylactic red blood cell (RBC) exchange in minor and/or bidirectional ABO mismatch of a second group of patients (study group) and investigated the incidence of hemolysis, transplant-related mortality (TRM), and overall survival (OS) and compared these data with the historical control group. Twenty-two of 80 patients in the study group had a minor and/or bidirectional ABO-mismatched donor. RESULTS: In 20 patients, a prophylactic RBC exchange was performed. Three patients showed mild to moderate citrate reactions, and in 1 patient the procedure had to be stopped because of hypotension. Eighteen of 20 patients engrafted uneventfully, 1 patient rejected his graft, and another 1 showed signs of mild hemolysis. In the minor and/or bidirectional ABO-mismatched setting patients in the study group had a lower risk for TRM at 1 year compared to patients in the historical control group (16% vs. 53%, p < 0.05) and a better 1-year OS (65% vs. 40%, p < 0.05). CONCLUSION: RBC exchange is a safe procedure, reducing the incidence of delayed severe immune hemolysis and thus the risk of TRM in minor and/or bidirectional ABO-mismatched cases.     

Red blood cell mass in autologous and homologous blood units. Implications for risk/benefit assessment of autologous blood crossover and directed blood transfusion

A prospective analysis of 300 consecutively collected homologous blood (HB) units from a regional blood center and an analysis of 188 consecutively collected autologous blood (AB) units from a community hospital was conducted. Analysis of the red blood cell (RBC) mass content of these blood units revealed that HB contained 13 percent more RBC than AB: 200 +/- 1.1 vs 177.1 +/- 1.1 mL, (m +/- SE), respectively (p less than 0.05). Of 174 AB units eligible for crossover by AABB criteria for RBC mass (greater than or equal to 154 mL), 35 (20%) were below the 95 percent confidence interval range for RBC mass of HB units collected; mean RBC mass of 300 HB units was 12 percent greater than that of 174 AB units (200.1 +/- 1.1 vs 178.9 +/- 0.9 mL, p less than 0.001) and 20 percent greater than that of the 35 AB units outside the 95 percent confidence interval (200.1 +/- 1.1 vs 161.2 +/- 0.5 mL, p less than 0.001). These findings indicate that an evaluation of the issues of AB crossover for HB transfusion should include a risk/benefit analysis of AB units with lower RBC mass. These findings also indicate that the proposed changes in AABB standards regarding directed donation (DD) should consider the reduced benefits of DD units with lower RBC mass in a risk/benefit analysis of this practice, and support retention of homologous donor standards for directed donors.     

Disproportionate outdating of group A blood

The authors studied the factors responsible for the disproportionate outdating of group A blood compared with group O blood over a 6-month interval. Distribution, transfusion, and outdate data for 99,251 units of blood were collected from representative hospitals within the region served by the Atlanta Regional Red Cross Blood Center. Factors evaluated included: neonatal transfusion of type O blood to type A recipients; use of type O blood in emergencies or due to group-specific shortages; demographic donor and recipient differences; and blood importing practices. Of 43,757 group O units (44.1% of total) available for distribution, 2050 (4.7%) were outdated, compared with 3908 (10.7%) of 36,501 group A units (36.8% of total). One thousand two hundred and seventy-nine units of type O blood were transfused to recipients who were not type O, including 842 group A neonatal patients. A larger inner-city hospital, where 46.8 percent of recipients were group O and 29.2 percent were group A, accounted for 180 more group O and 509 fewer group A transfusions than would be expected if donor-recipient ABO distributions were the same. Three hundred and seventy-four more group A units were imported than were needed. ABO-mismatched transfusions due to shortage or emergency were insignificant. It was concluded that increased use of group O blood for neonatal transfusions, donor-recipient differences in blood group frequencies, and blood importing practices are the major factors that increase the rate of group A outdating.     

Transfusion management of sickle cell patients during bone marrow transplantation with matched sibling donor

BACKGROUND: Sickle cell disease (SCD) patients have unique transfusion considerations during bone marrow transplantation (BMT), including prophylaxis against stroke and alloimmunization. Characterization of transfusion requirements is important for blood bank and clinician patient management.
STUDY DESIGN AND METHODS: A retrospective analysis of red blood cell (RBC) and platelet (PLT) transfusion of SCD patients during myeloablative matched sibling donor (MSD) BMT at one institution from 1993 to 2007 was performed. Patient characteristics (RBC blood group antibodies, ABO-incompatible donor, BMT-related morbidity) and transfusion practices (RBC phenotype matching, transfusion threshold, and blood age) were assessed for effect on total RBC transfusion volumes.
RESULTS: Twenty-seven patients received MSD BMT with 96% survival and 0% rejection. Six alloimmunized patients received RBCs with extended phenotype matching (C, c, E, e, K, Fy^a, Jk^b), 14 nonalloimmunized received limited matching (C, c, E, e, K), and 7 did not have phenotype matching. Among 26 survivors, a median seven RBC transfusions (range, 3-15) and 13.5 PLT transfusions (range, 4-48) per patient were administered, equivalent to 64 mL/kg RBCs (range, 22-122 mL/kg) and 106 mL/kg PLTs (range, 26-343 mL/kg). BMT-related morbidity predicted increased RBC transfusions (p = 0.006). Venoocclusive disease was associated with greater RBC (p = 0.016) and PLT transfusion volumes (p = 0.016). Greater phenotype matching was associated with decreased RBC transfusions (p = 0.0247).
CONCLUSIONS: SCD patients have high transfusion support during MSD BMT. Communication of BMT complications to the blood bank is essential for transfusion inventory management. Phenotype matching decreased RBC transfusions in this cohort and warrants further investigation in SCD transfusion therapy.     

Increasing hemoglobin oxygen saturation levels in sickle trait donor whole blood prevents hemoglobin S polymerization and allows effective white blood cell reduction by filtration

BACKGROUND Red blood cell (RBC) components from donors with sickle cell trait (Hb AS) often occlude white blood cell (WBC) reduction filters. Techniques were investigated to successfully filter Hb AS donor blood by increasing the Hb oxygen saturation with storage bags and conditions suitable for transfusion products. STUDY DESIGN AND METHODS: Oxygenation kinetics were measured over 3 days in whole-blood units stored in standard-sized 600-mL polyvinylchloride (PVC) bags and whole-blood units divided into three equal parts and stored in standard-sized blood bags made from PVC, tri-2-(ethylhexyl)trimellitate (CLX) plastic, or Teflon. The filterability of Hb AS blood stored for 3 days was tested with whole-blood filters. RESULTS: Oxygen saturation levels did not increase in full whole-blood units from donors without sickle cell trait during 3 days of storage in 600-mL PVC bags. In divided Hb AS whole-blood units stored for 3 days, oxygen saturation levels increased from baseline levels of 45 to 56, 66, and 94 percent after storage in 600-mL PVC, CLX, and Teflon bags, respectively (n = 5, p < 0.02), and all components filtered completely. When full Hb AS whole-blood units from eight donors were stored for 3 days in 1.5-L CLX bags, all units filtered completely, but one had a high residual WBC count. CONCLUSION: Storage of Hb AS whole blood in large-capacity oxygen-permeable bags increases oxygen tension and allows more effective WBC reduction by filtration.     

主要ABO血型不合异基因造血干细胞移植后纯红细胞再生障碍

目的 研究主要ABO血型不合异基因造血干细胞移植（allo-HSCT）后患者纯红细胞再生障碍（PRCA）的发病情况及危险因素。方法 分析移植后患者PRCA的发病危险因素，比较抗A凝集素与抗B凝集素对红系造血恢复的影响。结果 100例ABO血型主要及主次要均不合allo-HSCT患者中，12例发生PRCA。A供O者9例，A供B者1例，B供O者2例。有抗A凝集素的患者（10例）较有抗B凝集素的患者（2例）易发生PRCA（P〈0．05）。PRCA的发生不影响急性移植物抗宿主病（GVHD）或巨细胞病毒（CMV）感染的发生。发生PRCA时血型转换的中位时问为150．5d，显著长于无PRCA发生患者（60．0d）（P〈0．05）；红系恢复的中位时间为203．5d，显著长于无PRCA发生患者（76．0d）（P〈0．05）。有抗A凝集素的患者血型转换中位时间为90．0d，显著长于有抗B凝集素的患者（55．0d）（P〈0．05）；红系恢复中位时间为98．0d，长于有抗B凝集素者（80．0d）（P〉0．05），但差异无统计学意义。结论 PRCA是ABO血型不合移植的合并症之一。A供O是主要ABO血型小合allo-HSCT后PRCA发病的危险因素。     

Transfusion to blood group A and O patients of group B RBCs that have been enzymatically converted to group O

BACKGROUND: The transfusion of ABO-incompatible RBCs is the leading cause of fatal transfusion reactions. Group O RBCs, lacking terminal immunodominant A and B sugars to which humans are immunized, are safe for transfusion to persons of any ABO blood group. With the use of a recombinant alpha-galactosidase to remove terminal galactose from group B RBCs, the safety and efficacy of enzyme-converted group-B-to-group-O (ECO) RBC components were studied in transfusion-dependent patients. STUDY DESIGN AND METHODS: Twenty-four patients (blood groups A and O) were randomly assigned to receive transfusion(s) of either ECO or control group O RBCs. If a second transfusion was given, the other blood component was administered. RESULTS: Twenty-one patients were given ECO RBCs; 18 also underwent control transfusions. One patient received only a small aliquot for RBC survival studies, instead of a full-unit transfusion, because his serum was incompatible with ECO RBCs. No adverse events occurred. Both ECO and control transfusions resulted in appropriate Hb increments and comparable (51)Cr-labeled RBC survival studies. One patient developed a transient, weak-positive DAT, without hemolysis. Two weeks after transfusion, 5 of 19 evaluable ECO RBC recipients had increases in anti-B titers. CONCLUSION: ECO RBCs were comparable to group O cells for safety and efficacy in this study. The clinical significance of the increase in anti-B and of occasional serologic incompatibilities with ECO RBCs is unclear. If strategies can be developed to remove A epitopes, enzymatic conversion could be used to create a universal (group O) donor blood supply.     

Factors associated with the avoidance of red blood cell transfusion after hematopoietic stem cell transplantation

BACKGROUND: Red blood cell (RBC) transfusion is required frequently for most patients after hematopoietic stem cell transplantation (HSCT). RBC transfusion, however, can be associated with adverse events including transfusion reactions, acquiring transmissible disease, and delayed recovery. Factors associated with avoidance of transfusion are not well documented. STUDY DESIGN AND METHODS: Data concerning RBC transfusions between Day 0 and Day +30 were analyzed for patients undergoing HSCT at a single Canadian transplant center between January 2002 and December 2007. RESULTS: Of 555 patients undergoing HSCT with complete RBC transfusion data, 59 patients (10.6%) did not require RBC transfusion in the first 30 days after HSCT. Univariate analysis showed no significant difference in age, graft source, donor type, or conditioning regimen between transfused and nontransfused patients. Factors that were significantly associated with avoidance of transfusion included male sex (p = 0.0013), diagnosis, specifically plasma cell dyscrasias (p < 0.0001), early‐stage disease (p = 0.006), and higher baseline hemoglobin (Hb) at time of transplant (p < 0.0001). In multivariate analysis, higher pretransplant Hb, male sex, and early‐stage disease remained significantly associated with avoidance of RBC transfusion. Pretransplant Hb correlated inversely with the number of RBC transfusions (r = ?0.89). CONCLUSION: Increased pretransplant Hb, male sex, and early‐stage disease are associated with avoidance of RBC transfusion after HSCT. Interventions aimed at improving pretransplant Hb levels require further study.