Hemostatic properties and protein expression profile of therapeutic apheresis plasma treated with amotosalen and ultraviolet A for pathogen inactivation.

BACKGROUND: The INTERCEPT Blood System (IBS) using amotosalen-HCl and ultraviolet (UV)A inactivates a large spectrum of microbial pathogens and white blood cells in therapeutic plasma. Our aim was to evaluate to what extent IBS modifies the capacity of plasma to generate thrombin and induces qualitative or quantitative modifications of plasma proteins. STUDY DESIGN AND METHODS: Plasma units from four donors were collected by apheresis. Samples were taken before (control [CTRL]) and after IBS treatment and stored at -80°C until use. The activities of plasma coagulation factors and inhibitors and the thrombin generation potential were determined using assays measuring clotting times and the calibrated automated thrombogram (CAT), respectively. The proteomic profile of plasma proteins was examined using a two-dimensional differential in-gel electrophoresis (2D-DIGE) method. RESULTS: Nearly all of the procoagulant and antithrombotic factors tested retained at least 78% of their initial pre-IBS activity. Only FVII and FVIII displayed a lower level of conservation (67%), which nevertheless remained within the reference range for conventional plasma coagulation factors. The thrombin generation profile of plasma was conserved after IBS treatment. Among the 1331 protein spots revealed by 2D-DIGE analysis, only four were differentially expressed in IBS plasma compared to CTRL plasma and two were identified by mass spectrometric analysis as transthyretin and apolipoprotein A1. CONCLUSION: The IBS technique for plasma moderately decreases the activities of plasma coagulation factors and antithrombotic proteins, with no impact on the thrombin generation potential of plasma and very limited modifications of the proteomic profile.

Dehydration of blood platelets by zeodration: in vitro characterization and hemostatic properties in vivo.

BACKGROUND: Platelets (PLTs) are currently stored at room temperature (RT) for 5 to 7 days. So far, there exists no validated method for the preparation and long-term storage of dehydrated PLTs suitable for transfusion after rehydration. In this study, a desiccation process, zeodration, was applied to PLTs. STUDY DESIGN AND METHODS: A complete procedure of dehydration at RT by zeodration was employed. Zeodrated human and mouse PLTs were characterized in vitro. Zeodrated mouse PLTs were transfused into clopidogrel-treated mice to evaluate their hemostatic properties. RESULTS: The optimal conditions for dehydration of PLTs at RT in a laboratory scale zeodrator were defined as 145 mbar and 20.2 ± 1.5 °C. The recovery rate was 85 ± 2% and the dryness of zeodrated PLTs (Z_PLTs) indicated that they were sufficiently stable for long-term storage. Rehydrated Z_PLTs were round, were not aggregated, and expressed the glycoproteins required for PLT function. Z_PLTs agglutinated in the presence of von Willebrand factor (VWF) and aggregated in response to thrombin or collagen independently of an active metabolism. In a flow system, Z_PLTs could adhere to VWF and form aggregates on a collagen matrix. Thrombin was generated at the surface of Z_PLTs as efficiently as on fresh PLTs. In clopidogrel-treated mice, which exhibited a severely prolonged bleeding time, continuous perfusion of Z_PLTs restored normal hemostasis. CONCLUSION: Zeodration represents a new strategy to prepare PLTs with partly preserved aggregative properties after storage and rehydration. Z_PLTs have potential hemostatic properties provided it is possible to improve their transfusion efficacy.

Comparative effectiveness of plasma prepared with amotosalen-UVA pathogen inactivation and conventional plasma for support of liver transplantation.

BACKGROUND: Liver transplant may require large-volume plasma transfusion with increased risk of transfusion-transmitted infection (TTI). Pathogen inactivation of plasma with amotosalen-UVA offers the potential to mitigate TTI risk. STUDY DESIGN AND METHODS: A retrospective cohort design was used to compare the therapeutic efficacy and key safety outcomes for liver transplants supported with quarantine plasma (Q-FFP [reference]) or amotosalen-UVA plasma (IBS plasma [test]). The outcomes evaluated were volume of plasma, the numbers of red blood cell (RBC) components, and the total dose of platelets (PLTs) transfused during and 7 days after transplant. The safety outcomes were acute hepatic artery thrombosis (HAT) and mortality. RESULTS: Transplantation and transfusion records for 212 Q-FFP transplants and 215 IBS plasma transplants were reviewed. Not all transplants required plasma; 161 received Q-FFP and 174 received IBS plasma. Among the transplants that required plasma, there were significant differences in median values between cohorts for delay to transplantation (p=0.002), model end-stage liver disease score (p<0.001), pretransplant hematocrit (p=0.006), and graft cold perfusion time (p=0.033). The median volumes of plasma transfused were not different for test and reference (2.160 L vs. 1.969 L, p=0.292). Transplants in the test cohort required a mean of 3.7% more RBC components (p=0.767) and on average a 16.5% increase in total PLT dose (p=0.518). No significant differences were observed for the frequency of acute HAT or mortality. CONCLUSION: In this retrospective study, IBS plasma provided therapeutic support of liver transplant not different from Q-FFP.

Proteome changes in platelets after pathogen inactivation--an interlaboratory consensus.

Pathogen inactivation (PI) of platelet concentrates (PCs) reduces the proliferation/replication of a large range of bacteria, viruses, and parasites as well as residual leucocytes. Pathogen-inactivated PCs were evaluated in various clinical trials showing their efficacy and safety. Today, there is some debate over the hemostatic activity of treated PCs as the overall survival of PI platelets seems to be somewhat reduced, and in vitro measurements have identified some alterations in platelet function. Although the specific lesions resulting from PI of PCs are still not fully understood, proteomic studies have revealed potential damages at the protein level. This review merges the key findings of the proteomic analyses of PCs treated by the Mirasol Pathogen Reduction Technology, the Intercept Blood System, and the Theraflex UV-C system, respectively, and discusses the potential impact on the biological functions of platelets. The complementarities of the applied proteomic approaches allow the coverage of a wide range of proteins and provide a comprehensive overview of PI-mediated protein damage. It emerges that there is a relatively weak impact of PI on the overall proteome of platelets. However, some data show that the different PI treatments lead to an acceleration of platelet storage lesions, which is in agreement with the current model of platelet storage lesion in pathogen-inactivated PCs. Overall, the impact of the PI treatment on the proteome appears to be different among the PI systems. Mirasol impacts adhesion and platelet shape change, whereas Intercept seems to impact proteins of intracellular platelet activation pathways. Theraflex influences platelet shape change and aggregation, but the data reported to date are limited. This information provides the basis to understand the impact of different PI on the molecular mechanisms of platelet function. Moreover, these data may serve as basis for future developments of PI technologies for PCs. Further studies should address the impact of both the PI and the storage duration on platelets in PCs because PI may enable the extension of the shelf life of PCs by reducing the bacterial contamination risk.

Preserved functional and biochemical characteristics of platelet components prepared with amotosalen and ultraviolet A for pathogen inactivation.

BACKGROUND: Platelet concentrate (PC) functionality decreases during storage. This is referred to as the storage lesion. Pathogen inactivation may accelerate or induce lesions, potentially accounting for reduced viability. Our aim was to characterize functional and biochemical properties of platelets (PLTs) from photochemically treated buffy-coat PCs (PCT-PCs) compared to those from conventional PCs. STUDY DESIGN AND METHODS: Four PCT-PCs and four conventional PCs were stored for 6.5 days and PLT function and proteomic profiles were examined at various time points during storage. To evaluate their intrinsic properties, samples of stored PLTs were taken, washed, and suspended in Tyrode's buffer before testing. RESULTS: PLT counts and morphology were conserved although a slight increase in the PLT volume was observed after PCT. Glycoprotein (GP) IIbIIIa, IaIIa, and VI expression remained stable while GPIbα declined similarly in both types of PCs. A steep decrease (50%) in GPV occurred on Day 1.5 in PCT-PCs and Day 2.5 in control PCs. For both PCT- and control PCs, P-selectin expression and activated GPIIbIIIa remained low during storage. PCT- and control PCs were fully responsive to aggregation agonists up to Day 4.5 and exhibited similar perfusion functionality. Mitochondrial membrane potential and annexin A5 binding of PCT-PCs and control PCs were comparable. Two-dimensional differential in-gel electrophoresis and mass spectrometry profiles for 1882 protein spots revealed only three proteins selectively changed in PCT-PCs compared to control-PCs. CONCLUSION: Washed treated and untreated PCs have similar functional, morphologic, and proteomic characteristics provided that PLTs are suspended in an appropriate medium during testing.

HLA-DQA2 and HLA-DQB2 genes are specifically expressed in human Langerhans cells and encode a new HLA class II molecule.

The precise role of human epidermal Langerhans cells (LCs) in immune response is highly controversial. While studying the gene expression profile of these cells, we were intrigued to identify the HLA-DQB2 gene as potentially expressed in LCs. Despite a strong evolutionary conservation of their sequences, the concomitant expression of the poorly polymorphic HLA-DQA2/HLA-DQB2 genes, paralogous to the HLA-DQA1/HLA-DQB1 genes, has never been detected in any cell type. We confirmed by RT-PCR that the HLA-DQA2 and -DQB2 genes are both expressed in LCs, but not in monocyte-derived dendritic cells, or in blood CD1c(+) or plasmacytoid dendritic cells. The presence of the HLA-DQß2 chain in LCs could be demonstrated by Western blotting, whereas immunofluorescence revealed its localization in early endosomes. As in the case of other HLA class II molecules, the HLA-DQα2 and -DQß2 chains formed heterodimers that had to associate with the invariant chain to reach endosomal compartments. HLA-DQα2/ß2 heterodimers were expressed at the cell surface, where they could mediate staphylococcal superantigen stimulation of T cells. Interestingly, HLA-DQα2 and HLA-DQß1 chains formed mixed heterodimers which efficiently left the endoplasmic reticulum. These observations strongly suggest that the poorly polymorphic HLA-DQA2 and -DQB2 genes should be considered to be of immunological importance. The HLA-DQα2/ß2 molecules could influence the complexity of the repertoire of Ags presented by LCs.

Hirudin and heparin enable efficient megakaryocyte differentiation of mouse bone marrow progenitors.

Hematopoietic progenitors from murine fetal liver efficiently differentiate in culture into proplatelet-producing megakaryocytes and have proved valuable to study platelet biogenesis. In contrast, megakaryocyte maturation is far less efficient in cultured bone marrow progenitors, which hampers studies in adult animals. It is shown here that addition of hirudin to media containing thrombopoietin and serum yielded a proportion of proplatelet-forming megakaryocytes similar to that in fetal liver cultures (approximately 50%) with well developed extensions and increased the release of platelet particles in the media. The effect of hirudin was maximal at 100 U/ml, and was more pronounced when it was added in the early stages of differentiation. Hirugen, which targets the thrombin anion binding exosite I, and argatroban, a selective active site blocker, also promoted proplatelet formation albeit less efficiently than hirudin. Heparin, an indirect thrombin blocker, and OTR1500, a stable heparin-like synthetic glycosaminoglycan generated proplatelets at levels comparable to hirudin. Heparin with low affinity for antithrombin was equally as effective as standard heparin, which indicates antithrombin independent effects. Use of hirudin and heparin compounds should lead to improved culture conditions and facilitate studies of platelet biogenesis in adult mice.

Characterization of megakaryocyte development in the native bone marrow environment.

Differentiation and maturation of megakaryocytes occur in close association with cellular and extracellular components in the bone marrow. Thus, direct examination of these processes in the native environment provides important information regarding the development of megakaryocytes. In this chapter, we present methods applied to mouse bone marrow to (1) examine the ultrastructure of megakaryocytes and their state of maturation in situ in fixed bone marrow sections and (2) study the dynamics of proplatelet formation by real-time observation of fresh bone marrow explants where megakaryocytes have matured in their natural physiological context. Combining these two approaches allows detailed investigation of in situ megakaryocyte differentiation, including proplatelet formation, which is the final maturation step before platelet release.

Major contribution of the P2Y1receptor in purinergic regulation of TNFα-induced vascular inflammation.

BACKGROUND: Atherosclerosis is an inflammatory disease, and extracellular nucleotides are one of the factors possibly involved in vascular inflammation. The P2Y(1) receptor for adenosine 5'-diphosphate has been shown to be involved in the development of atherosclerosis in apolipoprotein E--deficient mice. Our aim is to determine whether the endothelial P2Y(1) receptor plays a role in leukocyte recruitment during vascular inflammation and characterize underlying mechanisms. METHODS AND RESULTS: We show here that the P2Y(1) receptor plays a role in leukocyte recruitment in inflamed mouse femoral arteries. Moreover, in wild-type bone marrow--transplanted chimeric P2Y(1)-deficient mice with an apolipoprotein E--deficient background, a strong reduction of adhesion molecule--dependent leukocyte recruitment was observed after local injection of tumor necrosis factor and interleukin 1ß, excluding a role for the platelet or other hematopoietic cell type P2Y(1) in these events. Similarly, the in vitro adhesion of isolated mouse monocytes to tumor necrosis factor α--stimulated murine endothelial cell monolayers and their migration across the cell layers were strongly reduced in P2Y(1)-deficient compared with wild-type endothelial cells, as was the expression of the adhesion molecules P-selectin, Vascular cell adhesion molecule 1, and intercellular adhesion molecule 1. Pharmacological inhibition using the selective antagonist MRS2500 also resulted in decreased expression of adhesion molecules. These events are related to the p38 mitogen-activated protein kinase and activating transcription factor 2 pathway. Finally, in vivo administration of MRS2500 resulted in strong reduction of leukocyte recruitment in inflamed femoral arteries of apolipoprotein E--deficient mice. CONCLUSIONS: The data highlight a key role of the endothelial P2Y(1) receptor in acute vascular inflammation. Pharmacological targeting the P2Y(1) receptor could represent a promising approach for the treatment of vascular inflammation.

Increased flexibility and liposome-binding capacity of CD1e at endosomal pH.

The plasma membrane proteins CD1a, CD1b and CD1c are expressed by human dendritic cells, the professional antigen-presenting cells of the immune system, and present lipid antigens to T lymphocytes. CD1e belongs to the same family of molecules, but accumulates as a membrane-associated form in the Golgi compartments of immature dendritic cells and as a soluble cleaved form in the lysosomes of mature dendritic cells. In lysosomes, the N-terminal propeptide of CD1e is also cleaved, but the functional consequences of this step are unknown. Here, we investigated how the pH changes encountered during transport to lysosomes affect the structure of CD1e and its ligand-binding properties. Circular dichroism studies demonstrated that the secondary and tertiary structures of recombinant CD1e were barely altered by pH changes. Nevertheless, at acidic pH, guanidium chloride-induced unfolding of CD1e molecules required lower concentrations of denaturing agent. The nonfunctional L194P allelic variant was found to be structurally less stable at acidic pH than the functional forms, providing an explanation for the lack of its detection in lysosomes. The number of water-exposed hydrophobic patches that bind 8-anilinonaphthalene-1-sulfonate was higher in acidic conditions, especially for the L194P variant. CD1e molecules interacted with lipid surfaces enriched in anionic lipids, such as bis(monoacylglycero)phosphate, a late endosomal/lysosomal lipid, especially at acidic pH, or when the propeptide was present. Altogether, these data indicate that, in the late endosomes/lysosomes of DCs, the acid pH promotes the binding of lipid antigens to CD1e through increased hydrophobic and ionic interactions.

The antithrombotic activity of EP224283, a neutralizable dual factor Xa inhibitor/glycoprotein IIbIIIa antagonist, exceeds that of the coadministered parent compounds.

EP224283 combines in a single molecule idraparinux and tirofiban, which allows obtaining a predictable and sustained antiplatelet effect through the transfer of the pharmacokinetics properties of idraparinux to the anti-αIIbß3 antagonist. The activity can be instantaneously neutralized by injection of avidin, a specific antidote. We have tested the effects of this new profile anticoagulant in various thrombosis models. The antithrombotic effect of EP224283 was compared with those of the parent compounds used alone or in association at doses achieving low to moderate inhibition of platelet aggregation ex vivo. In a model of systemic thromboembolism independent of thrombin generation, tirofiban and EP224283 had similar effects at equimolar doses. On the other hand, EP224283 was more potent than tirofiban or idraparinux under thrombin-dependent conditions. In a ferric chloride-induced thrombosis model, EP224283 was more potent than either parent compound or their combination. Similar results were obtained after atherosclerotic plaque rupture in ApoE(-/-) mice. Thus, the dual action of EP224283 exceeds that of the parent compounds used in combination. A possible explanation is that EP224283 could concentrate antithrombin inside the thrombus by binding to αIIbß3 through the tirofiban moiety, as shown by immunolabeling of the occluded vessel. No prolongation of the bleeding time was observed at doses achieving strong antithrombotic effects, suggesting that low to moderate αIIbß3 inhibition combined with factor Xa inhibition minimizes the bleeding risk. The favorable antithrombotic profile of EP224283 together with its possible neutralization by avidin makes it an interesting drug candidate for the treatment and prevention of acute ischemic events.

Use of additive solutions and pathogen inactivation treatment of platelet components in a regional blood center: impact on patient outcomes and component utilization during a 3-year period.

BACKGROUND: The Etablissement Français du Sang Alsace (EFS Alsace) successively implemented universal use of platelet additive solutions (PASs) and pathogen inactivation (PI) for platelet components (PCs). To assess the impact of these changes, EFS Alsace evaluated PC use, red blood cell (RBC) component use, and transfusion-related adverse events after implementation of these new technologies. STUDY DESIGN AND METHODS: EFS Alsace prospectively collects data on production, distribution, and response to transfusion of all blood components with greater than 99.5% data acquisition. Adverse events attributed to platelet (PLT) transfusions were collected through a mandatory, active hemovigilance program. A retrospective review of prospectively collected data was conducted covering three periods: 1) apheresis and whole blood-derived PCs in plasma, 2) apheresis and whole blood-derived PCs with PAS, and 3) PCs prepared with PI and PAS. Data on component utilization were analyzed for all patients receiving PCs in each period and for the subset of hematology-oncology patients to evaluate PC use in an intensely transfused population. Values for all continuous variables were summarized as mean and standard deviation, median, and range. RESULTS: Approximately 2000 patients received PCs in each period. PLT and RBC use per patient was not increased after PI (analysis of variance, F = 1.9 and 2.9, respectively) and the incidence of acute transfusion reactions was significantly reduced (p < 0.001). CONCLUSIONS: Universal use of PI was implemented without impacting component use, as indicated by total dose of PLTs per patient, and outcomes to transfusion were improved.

An active hemovigilance program characterizing the safety profile of 7483 transfusions with plasma components prepared with amotosalen and UVA photochemical treatment.

BACKGROUND: Photochemical pathogen inactivation treatment (PCT) of plasma components with amotosalen and UVA has been implemented in Europe. To establish a postapproval safety database, an active hemovigilance (HV) program utilizing an electronic data capture system (EDCS) was initiated. STUDY DESIGN AND METHODS: The response to transfusion was documented after each PCT-plasma transfusion. The primary outcome was the incidence of acute transfusion reactions (ATRs) within 24 hours of transfusion. An ATR was defined as an adverse event (AE) possibly related, probably related, or related to the PCT-plasma transfusion. For AEs, the following were collected: time of event after transfusion, clinical description, vital signs, clinical and laboratory test results, severity (Grade 0-4), seriousness, and causal relationship to transfusion of PCT-plasma. RESULTS: To date, 3232 patients (59.1% male) with a primary indication for plasma transfusion due to a hematology disorder (23.1%), surgery (32.4%), or a general medical condition (44.4%) received 7483 PCT-plasma transfusions (composed of 19,069 apheresis plasma components). The mean age of the patient population was 57.3 years (2884 adults, 160 children, and 188 infants). ATRs were reported for 8/7483 transfusions (0.11%; 95% confidence interval [CI], 0.03-0.19) and 8/3232 patients (0.25%; 95% CI, 0.08-0.42%). Five ATRs were of Grade 1 severity. The remaining three ATRs were classified as serious. No deaths or episodes of transfusion-related acute lung injury attributed to a PCT-plasma transfusion were reported. CONCLUSION: PCT-plasma transfusions were well tolerated in routine clinical use. The EDCS HV program facilitated collection and reporting of safety information on a real-time basis from multiple sites.

Feasibility study of a screening assay that identifies the abnormal prion protein PrPTSE in plasma: initial results with 20,000 samples.

BACKGROUND: It is likely that transmission of variant Creutzfeldt-Jakob disease (vCJD) occurs by transfusion and that the candidate infectious agent (PrP(TSE)) is present in small concentrations in the blood of infected donors in the asymptomatic phase of the disease. A new blood screening assay has been developed to detect PrP(TSE) in citrated plasma samples. STUDY DESIGN AND METHODS: Three regional Blood Transfusion Establishments (ETS) in France (ETS Alsace, ETS Bourgogne Franche-Comté, and ETS Pyrénées-Méditerranée) will screen 60,000 plasma samples (20,000 in each ETS) over a time period of approximately 9 to 12 months. RESULTS: Results provided in this report are those of the first testing site in Strasbourg, Alsace. The preliminary results have demonstrated an initial specificity of 97.60%. Upon repeat testing the specificity rate achieved 99.90% (20 repeat-positive samples). Based on the known epidemiology of vCJD in France, it is likely that the repeat-reactive samples are not true-positives. CONCLUSION: The screening assay was studied in terms of specificity and practicality and was found to be suitable for use in routine testing of blood donations. However, throughput must be enhanced by automation of the assay, and traceability would be improved if automated systems were used to distribute and identify samples.

[Universal implementation of pathogen inactivation in labile blood products is a major step towards transfusion safety]. / La mise en place universelle de l'inactivation des agents pathogènes dans les produits sanguins labiles est une étape majeure de l'amélioration de la sécurité en transfusion.

Transfusion of labile blood products (red cell concentrates, platelet concentrates and plasma) is vital in the absence of alternatives. Patients and doctors have always feared infections transmitted by blood, blood components and blood-derived drugs. It is potentially dangerous to delay implementation of pathogen inactivation in labile blood products pending a perfect process. Universal implementation of pathogen inactivation in labile blood products is a major step towards transfusion safety.

Intrinsic impaired proplatelet formation and microtubule coil assembly of megakaryocytes in a mouse model of Bernard-Soulier syndrome.

BACKGROUND: Giant platelets and thrombocytopenia are invariable defects in the Bernard-Soulier syndrome caused by deficiency of the GPIb-V-IX complex, a receptor for von Willebrand factor supporting platelet adhesion to the damaged arterial wall. Various properties of this receptor may be considered potential determinants of the macrothrombocytopenia. DESIGN AND METHODS: To explore the underlying mechanisms of the disease, megakaryopoiesis was studied in a mouse model deficient in GPIbbeta. Megakaryocytes were initially characterized in situ in the bone marrow of adult mice, after which their capacity to differentiate into proplatelet-bearing cells was evaluated in cultured fetal liver cells. RESULTS: The number of megakaryocyte progenitors, their differentiation and progressive maturation into distinct classes and their level of endoreplication were normal in GPIbbeta(-/-) bone marrow. However, the more mature cells exhibited ultrastructural anomalies with a thicker peripheral zone and a less well developed demarcation membrane system. GPIbbeta(-/-) megakaryocytes could be differentiated in culture from Lin(-) fetal liver cells in normal amounts but the proportion of cells able to extend proplatelets was decreased by 41%. Moreover, the GPIbbeta(-/-) cells extending proplatelets displayed an abnormal morphology characterized by fewer pseudopodial extensions with thicker shaft sections and an increased diameter of the terminal coiled elements. GPIbbeta(-/-) released platelets were larger but retained a typical discoid shape. Proplatelet formation was similarly affected in bone marrow explants from adult mice examined by videomicroscopy. The marginal microtubular ring contained twice as many tubulin fibers in GPIbbeta(-/-) proplatelet buds in cultured and circulating platelets. CONCLUSIONS: Altogether, these findings point to a role of the GPIb-V-IX complex intrinsic to megakaryocytes at the stage of proplatelet formation and suggest a functional link with the underlying microtubular cytoskeleton in platelet biogenesis.

Transfusion of platelet components prepared with photochemical pathogen inactivation treatment during a Chikungunya virus epidemic in Ile de La Réunion.

BACKGROUND: During the Chikungunya virus (CHIKV) epidemic on Ile de La Réunion, France, more than 30% of 750,000 inhabitants were infected. Local blood donation was suspended to prevent transfusion-transmitted infection (TT-CHIKV). To sustain the availability of platelet (PLT) components, the Etablissement Français du Sang implemented universal pathogen inactivation (INTERCEPT, Cerus Europe BV) of PLT components (CPAs). The study assessed the safety of PLT components treated with pathogen inactivation transfused in routine clinical practice. STUDY DESIGN AND METHODS: This was a retrospective observational study using patient medical records and the AFSSAPS hemovigilance database (eFIT) to identify TT-CHIKV and adverse events (AEs) classified as acute transfusion reactions (ATRs) to PLT components prepared with pathogen inactivation. RESULTS: During 1 year, 1950 INTERCEPT-CPAs were transfused to 335 adult, 51 pediatric, and 41 infant patients. Nineteen AEs were observed in 15 patients and 10 were classified as ATRs. Eight ATRs occurred in 6 pediatric hematology-oncology patients. No ATRs were observed in infants. The most frequently reported signs and symptoms were Grade 1 urticaria, itching, chills, fever, and anxiety. No cases of transfusion-related acute lung injury, TT-sepsis, or TT-CHIKV were detected. CONCLUSIONS: INTERCEPT-CPAs were well tolerated in a broad range of patients, including infants. ATR incidence was low and when present ATRs were of mild severity.

The assembly of CD1e is controlled by an N-terminal propeptide which is processed in endosomal compartments.

CD1e displays unique features in comparison with other CD1 proteins. CD1e accumulates in Golgi compartments of immature dendritic cells and is transported directly to lysosomes, where it is cleaved into a soluble form. In these latter compartments, CD1e participates in the processing of glycolipid antigens. In the present study, we show that the N-terminal end of the membrane-associated molecule begins at amino acid 20, whereas the soluble molecule consists of amino acids 32-333. Thus immature CD1e includes an N-terminal propeptide which is cleaved in acidic compartments and so is absent from its mature endosomal form. Mutagenesis experiments demonstrated that the propeptide controls the assembly of the CD1e alpha-chain with beta(2)-microglobulin, whereas propeptide-deleted CD1e molecules are immunologically active. Comparison of CD1e cDNAs from different mammalian species indicates that the CD1e propeptide is conserved during evolution, suggesting that it may also optimize the generation of CD1e molecules in other species.