Fecal blood loss: A quantitative method of evaluating hemostasis in patients with thrombocytopenia.

Background: The purpose of our studies was to determine if fecal blood loss can provide a quantitative measure of bleeding at platelet counts of 20 000/μL or less in patients with hypoproliferative thrombocytopenia and to document the effects of different prophylactic platelet transfusion triggers on fecal blood loss.

Methods And Materials: Patients had an aliquot of their autologous red blood cells (RBCs) labeled with Cr. Following reinjection of their radiolabeled RBCs, all feces and a daily blood sample were collected to determine fecal blood loss per day.

Transfusion-related immunomodulation: gamma irradiation alters the effects of leukoreduction on alloimmunization.

Background: Adverse events following blood transfusion include allosensitization and generalized immunosuppression, collectively referred to as transfusion-related immune modulation. We evaluated the immunological effects of red blood cell (RBC) and platelet transfusions on alloantibody responses and on immunoregulatory cells in nonimmunosuppressed patients undergoing cardiovascular surgery.

Study Design And Methods: Patients were randomized to receive standard unmodified (STD), leukoreduced (LR), or leukoreduced and γ-irradiated (LRγ) RBCs.

Leukofiltration plus pathogen reduction prevents alloimmune platelet refractoriness in a dog transfusion model.

Human lymphocyte antigen alloimmunization to filter leukoreduced (F-LR) platelets occurs in about 18% of immunosuppressed thrombocytopenic hematology/oncology patients and represents a significant challenge for effective chemotherapy. In a dog platelet transfusion model, we have evaluated other methods of preventing alloimmune platelet refractoriness and demonstrated that successful methods in our dog model are transferable to man. In the present study, donor/recipient pairs were dog lymphocyte antigen DR-B incompatible (88% of the pairs), and recipient dogs received up to 8 weekly treated transfusions from a single donor (a highly immunogenic stimulus), or until platelet refractoriness.

Ultraviolet B irradiation in the prevention of alloimmunization in a dog platelet transfusion model.

Background: Alloimmune platelet (PLT) refractoriness remains a significant problem for chronically transfused patients with thrombocytopenia.

Study Design And Methods: In a dog PLT transfusion model, we evaluated ultraviolet B irradiation (UV-B) of donor PLTs-either alone or in combination with centrifuge leukoreduction (C-LR) or filtration leukoreduction (F-LR)-to prevent refractoriness to donor PLTs and to induce tolerance to standard (STD) PLTs from the same donor or to tertiary donors.

Results: Recipient acceptance rates for C-LR donor PLT transfusions were 14%, F-LR were 33%, and UV-B irradiated were 45% with no significant differences among the treatments given to the donor's PLTs.

C1q-binding anti-HLA antibodies do not predict platelet transfusion failure in Trial to Reduce Alloimmunization to Platelets study participants.

Background: In the Trial to Reduce Alloimmunization to Platelets (TRAP) study, 101 of 530 subjects became clinically refractory (CR) to platelets (PLTs) without lymphocytotoxicity assay (LCA)-detectable anti-HLA antibodies. The LCA only detects complement-binding antibodies and is less sensitive than newer assays. Utilizing a more sensitive bead-based assay that does not distinguish between complement-binding versus non-complement-binding antibodies, we have previously shown that while many LCA-negative (LCA-) patients do have anti-HLA antibodies, these low- to moderate-level antibodies do not predict refractoriness.

Further studies to evaluate methods of leucoreduction to prevent alloimmune platelet refractoriness and induce tolerance in a dog platelet transfusion model.

Objectives: Three leucoreduction filters were evaluated - when used alone or combined with centrifuge leucoreduction (C-LR) - to prevent alloimmune platelet refractoriness in a dog platelet transfusion model.

Materials And Methods: Donor platelet-rich plasma (PRP) or buffy coat (BC) platelets were either filter leucoreduced (F-LR) or F-LR/C-LR, (51) Cr radiolabelled and transfused. Weekly transfusions were given for up to 8 weeks or until platelet refractoriness.

The association between platelet transfusion and idiopathic pneumonia syndrome is unaffected by platelet product type.

Background: Methods used to produce platelet (PLT) components, pooling of PLT-rich plasma (PRP-PLT) and apheresis (AP-PLT), may variably contribute to the pathogenesis and severity of idiopathic pneumonia syndrome (IPS).

Study Design And Methods: We performed a retrospective cohort study of 906 allogeneic hematopoietic cell transplant recipients to examine associations between PLT product type and risks of developing IPS and dying after IPS onset. Proportional hazards models included separate terms for the sum of all PLT transfusions and the sum of PRP-PLT units received in the 3 or 7 days before IPS onset.

Quantitative Influence of ABO Blood Groups on Factor VIII and Its Ratio to von Willebrand Factor, Novel Observations from an ARIC Study of 11,673 Subjects.

ABO blood groups are known to influence the plasma level of von Willebrand factor (VWF), but little is known about the relationship between ABO and coagulation factor VIII (FVIII). We analyzed the influence of ABO genotypes on VWF antigen, FVIII activity, and their quantitative relationship in 11,673 participants in the Atherosclerosis Risk in Communities (ARIC) study. VWF, FVIII, and FVIII/VWF levels varied significantly among O, A (A1 and A2), B and AB subjects, and the extent of which varied between Americans of European (EA) and African (AA) descent.

Review of in vivo studies of dimethyl sulfoxide cryopreserved platelets.

A literature review was conducted to assess the efficacy and safety of dimethyl sulfoxide (DMSO) cryopreserved platelets for potential military use. In vivo DMSO cryopreserved platelet studies published between 1972 and June of 2013 were reviewed. Assessed were the methods of cryopreservation, posttransfusion platelet responses, prevention or control of bleeding, and adverse events.

Extended storage of buffy coat platelet concentrates in plasma or a platelet additive solution.

Background: Platelet (PLT) concentrates (PCs) prepared from whole blood in the United States are made using the PLT-rich plasma method. The PCs must be made within 8 hours of blood collection and stored for only 5 days. In Europe and Canada, PCs are made using the buffy coat (BC) method from whole blood held overnight at 22 °C and storage times may be up to 7 days.

Exploratory studies of extended storage of apheresis platelets in a platelet additive solution (PAS).

To evaluate the poststorage viability of apheresis platelets stored for up to 18 days in 80% platelet additive solution (PAS)/20% plasma, 117 healthy subjects donated platelets using the Haemonetics MCS+, COBE Spectra (Spectra), or Trima Accel (Trima) systems. Control platelets from the same subjects were compared with their stored test PAS platelets by radiolabeling their stored and control platelets with either (51)chromium or (111)indium. Trima platelets met Food and Drug Administration poststorage platelet viability criteria for only 7 days vs almost 13 days for Haemonetics platelets; ie, platelet recoveries after these storage times averaged 44 ± 3% vs 49 ± 3% and survivals were 5.

Leukoreduction and ultraviolet treatment reduce both the magnitude and the duration of the HLA antibody response.

Background: Both leukoreduction and ultraviolet (UV) light treatment of blood products have been shown to reduce the incidence of HLA antibody development in recipients, but the impact of these treatments on the magnitude and persistence of the antibody response is less clear.

Study Design And Methods: Longitudinal samples from 319 subjects taken from four different study cohorts were evaluated for HLA antibodies to determine the effects of leukoreduction and UV treatment on HLA antibody generation and persistence.

Results: Subjects receiving leukoreduced or UV-treated blood products were less likely to generate Class I HLA antibodies, and those receiving leukoreduced blood were also less likely to generate Class II HLA antibodies.

Factor VIII mutation and desmopressin-responsiveness in 62 patients with mild haemophilia A.

Utilization of the synthetic vasopressin analogue (1-deamino-8-D-arginine-vasopressin, DDAVP) in treatment of mild haemophilia A (MHA, specific clotting factor VIII activity level 0.05-0.4 IU mL(-1) ) is convenient and effective for many but not all patients.

Cocaine and specific cocaine metabolites induce von Willebrand factor release from endothelial cells in a tissue-specific manner.

Objective: Cocaine use is associated with arterial thrombosis, including myocardial infarction and stroke. Cocaine use results in increased plasma von Willebrand factor (VWF), accelerated atherosclerosis, and platelet-rich arterial thrombi, suggesting that cocaine activates the endothelium, promoting platelet-VWF interactions.

Approach And Results: Human umbilical vein endothelial cells, brain microvasculature endothelial cells, or coronary artery endothelial cells were treated with cocaine or metabolites benzoylecgonine, cocaethylene, norcocaine, or ecgonine methylester.

Low-level HLA antibodies do not predict platelet transfusion failure in TRAP study participants.

In the Trial to Reduce Alloimmunization to Platelets (TRAP) study, 101 of 530 participants became refractory to platelet transfusions without evidence of HLA or human platelet antigen (HPA) antibodies. We used a more sensitive bead-based assay to detect and quantify HLA antibodies and a qualitative solid-phase enzyme-linked immunosorbet assay for HPA to determine whether low-level antibodies could predict refractoriness in longitudinal panels from 170 lymphocytotoxicity assay (LCA)(-) and 20 LCA(+) TRAP participants. All TRAP recipients who previously tested LCA(+) were HLA antibody(+), using the bead-based system.

Extended storage of autologous apheresis platelets in plasma.

Background And Objectives: The purpose of our studies was to determine the effects of extended platelet storage on poststorage platelet viability.

Materials And Methods: Normal subjects were recruited to donate platelets using two different apheresis systems: either the COBE Spectra (n = 58) or the Haemonetics MCS+ (n = 84). Platelet recovery and survival data from the two systems were compared with each other and with in vitro measurements of the stored platelets.

Signal transducer and activator of transcription 3 (STAT3) regulates collagen-induced platelet aggregation independently of its transcription factor activity.

Background: Platelet hyperactivity induced by inflammation is a known risk factor for atherosclerosis and thrombosis, but its underlying mechanisms remain poorly understood.

Methods And Results: The signal transducer and activator of transcription 3 (STAT3) was activated in collagen-stimulated platelets. Activated STAT3 served as a protein scaffold to facilitate the catalytic interaction between the kinase Syk (spleen tyrosine kinase) and the substrate PLCγ2 to enhance collagen-induced calcium mobilization and platelet activation.

Platelet concentrates prepared after a 20- to 24-hour hold of the whole blood at 22°C.

Background: The Food and Drug Administration (FDA) requires that red blood cells must be refrigerated within 8 hours of whole blood collection. Longer storage of whole blood at 22°C before component preparation would have many advantages.

Study Design And Methods: Two methods of holding whole blood for 20 to 24 hours at room temperature were evaluated, refrigerated plates or a 23°C incubator.

Suppression of the immune response to FVIII in hemophilia A mice by transgene modified tolerogenic dendritic cells.

Current methods for eradicating clinically significant inhibitory antibodies to human factor VIII (hFVIII) in patients with hemophilia A rely on repeated delivery of high doses of factor concentrates for a minimum of many months. We hypothesize that tolerance can be induced more efficiently and reliably through hFVIII antigen presentation by tolerogenic dendritic cells (tDCs). In this study, we generated tDCs from hemophilia A mice and modified them with a foamy virus vector expressing a bioengineered hFVIII transgene.

Persistence of lymphocytotoxic antibodies in patients in the trial to reduce alloimmunization to platelets: implications for using modified blood products.

Patients with acute myelogenous leukemia undergoing induction chemotherapy have significant decreases in alloimmune platelet refractoriness if they receive filter-leukoreduced or UV-B-irradiated vs standard platelet transfusions (3%-5% vs 13%, respectively; P ≤ .03) with no differences among the treated platelet arms (Trial to Reduce Alloimmunization to Platelets). Therefore, measuring antibody persistence might identify the best platelets for transfusion.

Extended storage of platelet-rich plasma-prepared platelet concentrates in plasma or Plasmalyte.

Background: Using bacterial detection or pathogen reduction, extended platelet (PLT) storage may be licensed if PLT viability is maintained. The Food and Drug Administration (FDA)'s poststorage PLT acceptance guidelines are that autologous stored PLT recoveries and survivals should be 66 and 58% or greater, respectively, of each donor's fresh PLT data.

Study Design And Methods: Nonleukoreduced PLT concentrates were prepared from whole blood donations.

Suppression of FVIII inhibitor formation in hemophilic mice by delivery of transgene modified apoptotic fibroblasts.

The development of inhibitory antibodies to factor VIII (FVIII) is currently the most significant complication of FVIII replacement therapy in the management of patients with severe hemophilia A. Immune tolerance protocols for the eradication of inhibitors require daily delivery of intravenous FVIII for at least 6 months and are unsuccessful in 20-40% of treated patients. We hypothesize that tolerance can be induced more efficiently and reliably by delivery of FVIII antigen within autologous apoptotic cells (ACs).

Effects of pretransfusion warming of platelets to 35 degrees C on posttransfusion platelet viability.

Background: Three of four prior studies suggested that warming platelets (PLTs) to 37 degrees C before transfusion into patients with thrombocytopenia gave improved corrected PLT count increments.

Study Design And Methods: Eighteen normal subjects had apheresis PLTs collected that were stored at 22 degrees C for 5 days in two storage bags. One bag of PLTs was warmed to 35 degrees C before infusion, and one remained at 22 degrees C.