Patricia Shi

Regulatory B‐cell compartment in transfused alloimmunized and non‐alloimmunized patients with sickle cell disease

Transfusion therapy is a life‐sustaining treatment for patients with sickle cell disease (SCD), but can cause serious complications including alloimmunization. We previously reported diminished regulatory T cells (Tregs) and skewed Th2 responses in alloimmunized SCD patients. We hypothesized that the B cell regulatory (Breg) compartment, which controls Treg and Th differentiation, may also be compromised in allosensitized SCD patients. Phenotypically, we did not find differences in the frequency or numbers of CD24hiCD38hi and CD24hiCD27+ B cell subsets, both previously identified as human Bregs, between alloimmunized and non‐alloimmunized SCD patients on regular transfusions. However, at the functional level, CD19+ B cells from alloimmunized SCD patients expressed lower levels of IL‐10 following stimulation as compared with non‐alloimmunized patients (P < 0.05), and had reduced ability in inhibiting autologous CD14+ monocyte TNF‐α expression (P < 0.05). These findings suggest that Bregs from alloimmunized and non‐alloimmunized SCD patients differ in their ability to produce IL‐10 and dampen monocyte activation, all consistent with an altered immunoregulatory state in alloimmunized SCD patients. Am. J. Hematol. 88:736–740, 2013.

Results of lookback for Chagas disease since the inception of donor screening at New York Blood Center

BACKGROUND: Chagas disease is a parasitic infection by Trypanosoma cruzi, typically transmitted via infected triatomine bug fecal contamination of bite sites. Other routes of infection include congenital, oral, organ transplantation, and blood product transmission.

Altered heme-mediated modulation of dendritic cell function in sickle cell alloimmunization

Transfusions are the main treatment for patients with sickle cell disease. However, alloimmunization remains a major life-threatening complication for these patients, but the mechanism underlying pathogenesis of alloimmunization is not known. Given the chronic hemolytic state characteristic of sickle cell disease, resulting in release of free heme and activation of inflammatory cascades, we tested the hypothesis that anti-inflammatory response to heme is compromised in alloimmunized sickle patients, increasing their risk of alloimmunization. Heme-exposed monocyte-derived dendritic cells from both non-alloimmunized sickle patients and healthy donors inhibited priming of pro-inflammatory CD4+ type 1 T cells, and exhibited significantly reduced levels of the maturation marker CD83. In contrast, in alloimmunized patients, heme did not reverse priming of pro-inflammatory CD4+ cells by monocyte-derived dendritic cells or their maturation. Furthermore, heme dampened NF-κB activation in non-alloimmunized, but not in alloimmunized monocyte-derived dendritic cells. Heme-mediated CD83 inhibition depended on Toll-like receptor 4 but not heme oxygenase 1. These data suggest that extracellular heme limits CD83 expression on dendritic cells in non-alloimmunized sickle patients through a Toll-like receptor 4-mediated pathway, involving NF-κB, resulting in dampening of pro-inflammatory responses, but that in alloimmunized patients this pathway is defective. This opens up the possibility of developing new therapeutic strategies to prevent sickle cell alloimmunization.

Sustained treatment of sickle cell mice with haptoglobin increases HO-1 and H-ferritin expression and decreases iron deposition in the kidney without improvement in kidney function

There is growing evidence that extracellular haemoglobin and haem mediate inflammatory and oxidative damage in sickle cell disease. Haptoglobin (Hp), the scavenger for free haemoglobin, is depleted in most patients with sickle cell disease due to chronic haemolysis. Although single infusions of Hp can ameliorate vaso‐occlusion in mouse models of sickle cell disease, prior studies have not examined the therapeutic benefits of more chronic Hp dosing on sickle cell disease manifestations. In the present study, we explored the effect of Hp treatment over a 3‐month period in sickle mice at two dosing regimens: the first at a moderate dose of 200 mg/kg thrice weekly and the second at a higher dose of 400 mg/kg thrice weekly. We found that only the higher dosing regimen resulted in increased haem‐oxygenase‐1 and heavy chain ferritin (H‐ferritin) expression and decreased iron deposition in the kidney. Despite the decreased kidney iron deposition following Hp treatment, there was no significant improvement in kidney function. However, there was a nearly significant trend towards decreased liver infarction.

Case series supporting heme detoxification via therapeutic plasma exchange in acute multiorgan failure syndrome resistant to red blood cell exchange in sickle cell disease: HEME DETOXIFICATION VIA TPE WITH RCE-RESISTANT MOFS IN SCD

Depletion of haptoglobin (Hp) and hemopexin (Hx) with increase in free hemoglobin and heme are important etiologies of vaso‐occlusive complications in sickle cell disease (SCD). This study is the first to show an association between clinical improvement in SCD and repletion of Hp and Hx by therapeutic plasma exchange (TPE) using plasma replacement.

HO-1hi Patrolling Monocytes Protect against Vaso-occlusion in Sickle Cell Disease

Patients with sickle cell disease (SCD) suffer from intravascular hemolysis associated with vascular injury and dysfunction in mouse models, and painful vaso-occlusive crisis (VOC) involving increased attachment of sickle erythrocytes and activated leukocytes to damaged vascular endothelium. Patrolling monocytes, which normally scavenge damaged cells and debris from the vasculature, express higher levels of anti-inflammatory heme oxygenase 1 (HO-1), a heme degrading enzyme. Here, we show that HO-1-expressing patrolling monocytes protect SCD vasculature from ongoing hemolytic insult and vaso-occlusion. We found that a mean 37% of patrolling monocytes from SCD patients express very high levels of HO-1 (HO-1hi) vs 6% in healthy controls and demonstrated that HO-1hi expression was dependent on uptake of heme-exposed endothelium. SCD patients with a recent VOC episode had lower numbers of HO-1hi patrolling monocytes. Heme-mediated vaso-occlusion by mouse SCD red blood cells was exacerbated in mice lacking patrolling monocytes, and reversed following transfer of patrolling monocytes. Altogether, these data indicate that SCD patrolling monocytes remove hemolysis-damaged endothelial cells, resulting in HO-1 upregulation and dampening of VOC, and that perturbation in patrolling monocyte numbers resulting in lower numbers of HO-1hi patrolling monocyte may predispose SCD patients to VOC. These data suggest that HO-1hi patrolling monocytes are key players in VOC pathophysiology and have potential as therapeutic targets for VOC.

Current patterns of use in therapeutic apheresis: a metropolitan center experience

New York Blood Center (NYBC) performs apheresis for approximately 95 hospitals in the greater metropolitan area. The hospital mix is mostly urban, mostly public, and approximately equally teaching and nonteaching, with sizes ranging from small to large. Therefore NYBC’s case mix is probably representative of the distribution of apheresis procedures occurring for various diagnoses within the Northeast region. Of interest are the most frequent diagnoses for which apheresis is performed and whether an estimate of the number of procedures per patient seems reasonable for the diagnosis. A retrospective review of all 9374 apheresis procedures performed by the NYBC in 2011 and 2012 was performed. A NYBC physician review and approval was required before initiating new patients. Diagnoses were categorized whenever possible using the 2013 American Society for Apheresis (ASFA) guidelines. A total of 7193 (76.8%) apheresis procedures in 1289 patients were for therapeutic indications. The remaining procedures were hematopoietic progenitor cell or other mononuclear cell collections, predominantly for sipuleucel-T (autologous dendritic cell derived) prostate cancer treatment. Of the patients receiving therapeutic apheresis, 52% were male and 48% were female. Patient age ranged from 3 to 95 years old, with 11% being pediatric (<18 years old), 41% between 18 and 45 years, 30% between 45 and 65 years, and 18% more than 65 years. Of the total procedures, 81.9% were plasma exchanges, 15.1% were red blood cell exchanges (RCEs), 2.4% were leukapheresis procedures, and 0.1% were plateletpheresis procedures. A breakdown of individual diagnoses is listed in Table 1. A total of 88% of patients and 95% of procedures were done for either ASFA Grade I or II indications. A total of 11.9% of patients and 4.8% of procedures were done for ASFA Grade III indications; only one patient had an ASFA Grade IV indication (refractory idiopathic thrombocytopenic purpura). The most common indications for plasma exchange were thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), thrombotic microangiopathy, myasthenia gravis, and renal transplant desensitization or rejection. The precise fraction of patients with TTP versus HUS versus thrombotic microangiopathy is not available; however, more than 90% are recollected to be TTP cases. RCE was predominantly for sickle cell disease (SCD). Indications for RCE treatment in SCD were available for 88.5% of patients and 94% of procedures, with acute conditions being the indication for approximately 70% of SCD patients and 36% of RCE procedures. The remaining procedures were performed either preoperatively or for chronic prophylaxis (predominantly stroke and rarely pain crisis prophylaxis). Other diagnoses treated, which could not be ASFA categorized, possibly due to lack of information, include nonspecific polyneuropathy, nonspecific transverse myelitis, nonspecific vasculitis, and thrombocytopeniaassociated multiple organ failure. Additional information and/or outcome data would be required to clarify the appropriateness of therapeutic apheresis in these instances. Compared to the 2010 guidelines, the 2013 guidelines additionally included heparin-induced thrombocytopenia and Stevens-Johnson syndrome and/or toxic epidermal necrolysis (Category III indications) and the revision of polycythemia vera from a Category III to Category I indication, as reflected in Table 1. Monitoring of changes in practice helps us remain informed of new potential indications and to advise partnering institutions. Evidence-based guidelines for therapeutic apheresis are intended to advise and educate clinicians on the quality of evidence as well as the strength of recommendation based on published practice and outcomes. Based on our experience, the vast majority of procedures performed (>90%) fall into either Grade I or Grade II.

Donor Qualification for Hematopoietic Cell Transplantation

Donor qualification assessment is a critical step in ensuring the safety and efficacy of the hematopoietic progenitor cell (HPC) transplantation process. Donor qualification refers to aspects of the donor that may affect safety of the donor, safety of the recipient, and success of the HPC transplantation in the recipient. This definition is synonymous with the term “donor suitability” used by the World Marrow Donor Association (WMDA) and American Association of Blood Banks (AABB). However, the term donor qualification is used for clarity because the term donor suitability can have different connotations in various contexts. For example, in FACT accreditation parlance, donor suitability is defined more narrowly as issues “that relate to the general health or medical fitness of the donor to undergo the collection procedure.” In FDA parlance, in contrast, “donor suitability” is used interchangeably with “donor eligibility” or the infectious disease risk of the donor to recipient safety. The chapter provides an overview of the most important concepts in donor qualification assessment and a practical framework of how to systematically evaluate donor qualification.

Retrospective analysis of community hospital red blood cell recovery procedures: improved utilization needed for effectiveness

Perioperative blood recovery (PBR) is an important component of patient blood management. We analyzed our experience providing PBR for community hospitals to determine procedure types and clinical variables associated with efficacy and cost‐effectiveness.

Does recipient inflammation contribute to red blood cell alloimmunization

I n a paper by Telen and colleagues in this issue of TRANSFUSION, 285 subjects (of 338 adult SCD patients who were part of a larger study of clinical outcome-modifying genes) were available at Duke and the University of North Carolina to study recipient associations with alloimmunization. Data regarding lifetime number of transfusions, current chronic transfusion therapy, and opioid use were obtained through patient history at the time of enrollment rather than by medical record review, possibly because adults often receive transfusion care at multiple area hospitals. Although their use of multivariable regression was limited, Telen and colleagues found that alloimmunization was associated with opioid use, avascular necrosis, and decreased survival. This study performed in adults also found a higher alloimmunization prevalence of 27% compared to previous studies of 19 and 14%, both of which included children with presumably fewer lifetime transfusions. As previously reported and consistent with the fact that lifetime number of transfusion can be predictive of alloimmunization, patients with genotypes HbSS and HbSb0 had higher transfusion and alloimmunization rates than HbSC and HbSb1 patients. This higher alloimmunization prevalence was associated with antibodies to red blood cell (RBC) antigens S, M, Jkb, and V, leading to the question of whether adults should have extended matching beyond C, E, and K antigens alone. Is lifetime number of transfusions the primary determinant, however, of the risk of alloimmunization in sickle cell disease? Recent data from Chou and coworkers are consistent with this hypothesis, in that 58% of chronically versus 15% of episodically transfused patients became alloimmunized (mostly to Rh antigens). Other studies including this study, however, did not find the expected higher rate of alloimmunization in chronically transfused patients. Assuming that Rh antibodies were not misinterpreted as autoantibodies, how can these disparate results be reconciled? Further controlled prospective study is necessary, but these findings could be consistent with recipient inflammation contributing to alloimmunization risk. Human RBCs are generally poor immunogens, and why patients with sickle cell disease can have persistently high alloimmunization rates even with RhC, -E, and -K and ethnically matched donors is an area of active research. While donor or donor unit characteristics may play a role, recipient factors may also be important. Recipient factors such as immune regulatory polymorphisms, the microbiome, and microbial priming are intriguing areas of research, but substantial evidence for the importance of recipient inflammatory state holds promise for earlier therapeutic intervention with anti-inflammatory therapies. The association of warm autoantibodies with alloantibodies as reported in this study is well known, but autoantibodies can occur independently with transfusion and could be consistent with an inflammatory contribution, given the association of autoas well as anti-K antibodies with inflammation. Since vasoocclusive crisis and acute chest syndrome are inflammatory states possibly associated with alloimmunization, the absence of such associations in this study might be explained by the fact that the study data presented were the number of pain crisis in the 12 months preceding enrollment rather than in the 12 months preceding detection of specific alloantibody and acute chest syndrome by patient history rather than medical record review. The specific inflammatory pattern in the recipient may also possibly play a role. What this study did find, after only adjusting for sickle cell genotype, sex, and age, was a persistent association of alloimmunization with both avascular necrosis and daily opioid use, but not other types of end-organ damage. These associations could also be consistent with inflammation being a potential risk factor for alloimmunization, given evidence that chronic opioid use is associated with mast cell activation leading to an inflammatory state. Avascular necrosis may simply be a clinical indicator of daily opioid use rather than an actual risk factor itself, as it is difficult to understand why avascular necrosis as opposed to other types of end-organ damage would increase risk for alloimmunization. Indeed, this study in addition to another found these two variables to be highly correlated, with avascular necrosis conferring an odds ratio of at least 2 for daily opioid use, with p values of less than 0.01. A stepwise logistic regression for alloimmunization outcome including both avascular necrosis and daily opioid use, as well as other known predictors such as lifetime units of blood transfused, would be helpful in validating this hypothesis. A reasonable follow-up question is why leg ulcers, which also may require daily opioid use, were not also associated with alloimmunization? One explanation might be that the data presented was “history of leg ulcers,” which may have been transient, rather than the VC 2015 AABB doi:10.1111/trf.13058 TRANSFUSION 2015;55;1371–1373