Inactivation of Orientia tsutsugamushi in red blood cells, plasma, and platelets with riboflavin and light, as demonstrated in an animal model

Results of clinical effectiveness of conventional versus Mirasol-treated Apheresis Platelets in Patients with Hypoproliferative Thrombocytopenia (MiPLATE) trial

BACKGROUND

The Mirasol® Pathogen Reduction Technology System was developed to reduce transfusion-transmitted diseases in platelet (PLT) products.

STUDY DESIGN AND METHODS

MiPLATE trial was a prospective, multicenter, controlled, randomized, non-inferiority (NI) study of the clinical effectiveness of conventional versus Mirasol-treated Apheresis PLTs in participants with hypoproliferative thrombocytopenia. The novel primary endpoint was days of ≥Grade 2 bleeding with an NI margin of 1.6.

RESULTS

After 330 participants were randomized, a planned interim analysis of 297 participants (145 MIRASOL, 152 CONTROL) receiving ≥1 study transfusion found a 2.79-relative rate (RR) in the MIRASOL compared to the CONTROL in number of days with ≥Grade 2 bleeding (95% confidence interval [CI] 1.67-4.67). The proportion of subjects with ≥Grade 2 bleeding was 40.0% (n = 58) in MIRASOL and 30.3% (n = 46) in CONTROL (RR = 1.32, 95% CI 0.97-1.81, p = .08). Corrected count increments were lower (p < .01) and the number of PLT transfusion episodes per participant was higher (RR = 1.22, 95% CI 1.05-1.41) in MIRASOL. There was no difference in the days of PLT support (hazard ratio = 0.86, 95% CI 0.68-1.08) or total number of red blood cell transfusions (RR = 1.12, 95% CI 0.91-1.37) between MIRASOL versus CONTROL. Transfusion emergent adverse events were reported in 119 MIRASOL participants (84.4%) compared to 133 (82.6%) participants in CONTROL (p = NS).

DISCUSSION

This study did not support that MIRASOL was non-inferior compared to conventional platelets using the novel endpoint number of days with ≥Grade 2 bleeding in MIRASOL when compared to CONTROL.

Optimization of human platelet lysate production and pathogen reduction in a public blood transfusion center

BACKGROUND

Human platelet lysate (HPL) has been proposed as a safe and efficient xeno-free alternative to fetal bovine serum (FBS) for large-scale culturing of cell-based medicinal products. However, the use of blood derivatives poses a potential risk of pathogen transmission. To mitigate this risk, different pathogen reduction treatment (PRT) practices can be applied on starting materials or on final products, but these methods might modify the final composition and the quality of the products.

STUDY DESIGN AND METHODS

We evaluated the impact of applying a PRT based on riboflavin and ultraviolet irradiation on the raw materials used to manufacture an improved Good Manufacturing Practices (GMP)-grade HPL product in a public blood center. Growth promotion and the levels of growth factors and proteins were compared between an inactivated product (HPL4-i) and a non-inactivated product (HPL4). Stability studies were performed at 4°C, -20°C, and -80°C.

RESULTS

The application of a PRT on the starting materials significantly altered the protein composition of HPL4-i as compared with HPL4. Despite this, the growth promoting rates were unaffected when compared with FBS used as a control. While all products were stable at -20°C and -80°C for 24 months, a significant decrease in the activity of HPL4-i was observed when stored at 4°C.

CONCLUSION

Our results show that the application of a PRT based on riboflavin and ultraviolet light on starting materials used in the manufacture of HPL modifies the final composition of the product, yet its cell growth promoting activity is maintained at levels similar to those of non-inactivated products.

Pathogen reduction of blood components during outbreaks of infectious diseases in the European Union: an expert opinion from the European Centre for Disease Prevention and Control consultation meeting

Pathogen reduction (PR) of selected blood components is a technology that has been adopted in practice in various ways. Although they offer great advantages in improving the safety of the blood supply, these technologies have limitations which hinder their broader use, e.g. increased costs. In this context, the European Centre for Disease Prevention and Control (ECDC), in co-operation with the Italian National Blood Centre, organised an expert consultation meeting to discuss the potential role of pathogen reduction technologies (PRT) as a blood safety intervention during outbreaks of infectious diseases for which (in most cases) laboratory screening of blood donations is not available. The meeting brought together 26 experts and representatives of national competent authorities for blood from thirteen European Union and European Economic Area (EU/EEA) Member States (MS), Switzerland, the World Health Organization, the European Directorate for the Quality of Medicines and Health Care of the Council of Europe, the US Food and Drug Administration, and the ECDC. During the meeting, the current use of PRTs in the EU/EEA MS and Switzerland was verified, with particular reference to emerging infectious diseases (see Appendix). In this article, we also present expert discussions and a common view on the potential use of PRT as a part of both preparedness and response to threats posed to blood safety by outbreaks of infectious disease.

Efforts Toward Elimination of Infectious Agents in Blood Products

The US blood supply has never been safer. This level of safety depends on a multifaceted approach including blood donor screening, sensitive infectious disease testing, and good manufacturing practice. However, risks remain for transfusion-transmitted infections due to bacterial contamination of platelets and emerging diseases. Thus, ongoing improvements in screening and testing are required. Newer pathogen reduction technologies have shown promise in further ameliorating the safety of the blood supply.

Pathogen reduction and blood transfusion safety in Africa: strengths, limitations and challenges of implementation in low-resource settings

Transfusion-transmitted infection risk remains an enduring challenge to blood safety in Africa. A high background incidence and prevalence of the major transfusion-transmitted infections (TTIs), dependence on high-risk donors to meet demand, suboptimal testing and quality assurance collectively contribute to the increased risk. With few exceptions, donor testing is confined to serological evaluation of human immunodeficiency virus (HIV), hepatitis B and C (HBV and HCV) and syphilis. Barriers to implementation of broader molecular methods include cost, limited infrastructure and lack of technical expertise. Pathogen reduction (PR), a term used to describe a variety of methods (e.g. solvent detergent treatment or photochemical activation) that may be applied to blood following collection, offers the means to diminish the infectious potential of multiple pathogens simultaneously. This is effective against different classes of pathogen, including the major TTIs where laboratory screening is already implemented (e.g. HIV, HBV and HCV) as well pathogens that are widely endemic yet remain unaddressed (e.g. malaria, bacterial contamination). We sought to review the available and emerging PR techniques and their potential application to resource-constrained parts of Africa, focusing on the advantages and disadvantages of such technologies. PR has been slow to be adopted even in high-income countries, primarily given the high costs of use. Logistical considerations, particularly in low-resourced parts of Africa, also raise concerns about practicality. Nonetheless, PR offers a rational, innovative strategy to contend with TTIs; technologies in development may well present a viable complement or even alternative to targeted screening in the future.

Treatment of blood with a pathogen reduction technology using ultraviolet light and riboflavin inactivates Ebola virus in vitro

BACKGROUND

Transfusion of plasma from recovered patients after Ebolavirus (EBOV) infection, typically called "convalescent plasma," is an effective treatment for active disease available in endemic areas, but carries the risk of introducing other pathogens, including other strains of EBOV. A pathogen reduction technology using ultraviolet light and riboflavin (UV+RB) is effective against multiple enveloped, negative-sense, single-stranded RNA viruses that are similar in structure to EBOV. We hypothesized that UV+RB is effective against EBOV in blood products without activating complement or reducing protective immunoglobulin titers that are important for the treatment of Ebola virus disease (EVD).

STUDY DESIGN AND METHODS

Four in vitro experiments were conducted to evaluate effects of UV+RB on green fluorescent protein EBOV (EBOV-GFP), wild-type EBOV in serum, and whole blood, respectively, and on immunoglobulins and complement in plasma. Initial titers for Experiments 1 to 3 were 4.21 log GFP units/mL, 4.96 log infectious units/mL, and 4.23 log plaque-forming units/mL. Conditions tested in the first three experiments included the following: 1-EBOV-GFP plus UV+RB; 2-EBOV-GFP plus RB only; 3-EBOV-GFP plus UV only; 4-EBOV-GFP without RB or UV; 5-virus-free control plus UV only; and 6-virus-free control without RB or UV.

RESULTS

UV+RB reduced EBOV titers to nondetectable levels in both nonhuman primate serum (≥2.8- to 3.2-log reduction) and human whole blood (≥3.0-log reduction) without decreasing protective antibody titers in human plasma.

CONCLUSION

Our in vitro results demonstrate that the UV+RB treatment efficiently reduces EBOV titers to below limits of detection in both serum and whole blood. In vivo testing to determine whether UV+RB can improve convalescent blood product safety is indicated.

Inactivation of viruses in platelet and plasma products using a riboflavin-and-UV-based photochemical treatment

BACKGROUND

Multilayered blood safety programs reduce the risk of transfusion-transmitted diseases; however, there remains a risk of window period transmission of screened viruses and transmission of unscreened and emerging viruses from asymptomatic donors. To reduce this risk, a riboflavin-and-UV-light-based pathogen reduction process was evaluated against eight viral agents.

STUDY DESIGN AND METHODS

Riboflavin and UV light was evaluated against the following eight viral agents: encephalomyocarditis virus (EMC), hepatitis A virus (HAV), hepatitis C virus (HCV), influenza A (FLUAV), La Crosse virus (LACV), pseudorabies virus (PRV), sindbis virus (SINV), and vesicular stomatitis virus (VSV). Before treatment, a sample was removed to determine the product's initial viral load. After treatment the product's viral load was reevaluated and the log reduction was calculated.

RESULTS

Virus reduction after treatment with riboflavin and UV light is equivalent in platelet (PLT) and plasma units, as demonstrated by a 3.2-log reduction of EMC in plasma, PLTs, and PLT additive solution containing 35% plasma. Additionally, the following viral reductions values were observed: HAV 1.8 log, HCV at least 4.1 log, FLUAV at least 5.0 log, LACV at least 3.5 log, PRV 2.5 log, SINV 3.2 log, and VSV at least 6.3 log.

CONCLUSIONS

The results observed in this study suggest that treating PLT and plasma products with a riboflavin-and-UV-light-based pathogen reduction process could potentially eliminate window period transmission of screened viruses and greatly reduce the risk of transfusion transmission of unscreened viruses.

The effectiveness of riboflavin photochemical-mediated virus inactivation and changes in protein retention in fresh-frozen plasma treated using a flow-based treatment device

BACKGROUND

A flow-based treatment device using riboflavin and ultraviolet (UV) light was developed to inactivate viruses in fresh-frozen plasma (FFP). The objective of this study was to evaluate the in vitro effectiveness of virus inactivation and changes in protein quality in FFP treated with this device.

STUDY DESIGN AND METHODS

FFP-contaminating viruses were treated with riboflavin and UV light using a one-pass linear flow device. The infectivity of viruses was measured using established biologic assays. Real-time polymerase chain reaction (PCR) was performed to detect damage to viral nucleotides after treatment. Treated plasma was analyzed using standard coagulation assays.

RESULTS

FFP treated at the UV dose of 3.6 J/cm(2) (J) exhibited a mean reduction of virus titer of more than 4 logs. The effectiveness increased significantly at higher doses. Real-time PCR showed that the cycle threshold values for both complete inactivation and virus recultivation were higher than that of the untreated sample. At doses of 3.6, 5.4, and 7.2 J, the protein recovery rates were 60.2 ± 8.6, 46.6 ± 9.4, and 28.0 ± 1.0% for fibrinogen; 67.0 ± 3.1, 57.3 ± 8.0, and 49.2 ± 3.8% for Factor VIII; 93.6 ± 2.8, 89.6 ± 6.1, and 86.5 ± 5.3% for antithrombin-III; and 72.1 ± 5.6, 59.8 ± 14.2, and 49.2 ± 8.4% for Protein C, respectively.

CONCLUSION

The effectiveness of virus inactivation was enhanced, but total activity of plasma factors was reduced, in a UV dose-dependent manner.

Immune modulation and lack of alloimmunization following transfusion with pathogen-reduced platelets in mice

BACKGROUND

Transfusion of allogeneic blood products can lead to alloimmunization, impacting success of subsequent transfusions and solid organ transplants. Pathogen reduction using riboflavin and ultraviolet B (UVB) light has been shown to eliminate the immunogenicity of white blood cells (WBCs) in vitro through down regulation of surface adhesion molecules, effectively blocking cell-cell conjugation and direct presentation. We sought to determine if this loss of immunogenicity is extended in vivo where indirect presentation of allogeneic antigens can occur.

STUDY DESIGN AND METHODS

BALB/cJ mice were transfused with either untreated or riboflavin and UVB-treated C57Bl/6J platelet-rich plasma (PRP) containing WBCs. Circulating alloantibody and allospecific splenocyte cytokine responses were measured.

RESULTS

Pathogen reduction of allogeneic WBC-enriched PRP using riboflavin and UVB light before transfusion prevented alloimmunization, with a loss of both alloantibody generation and priming of secondary cytokine responses ex vivo. When mice given treated transfusions were subsequently given untreated transfusions, they produced normal levels of alloantibodies but had reduced secondary cytokine responses ex vivo. This immune modulation was antigen specific and was dependent on the presence of WBCs in the treated product.

CONCLUSIONS

UVB plus riboflavin treatment of WBC-enriched PRP effectively blocks alloimmunization and modulates immune responses to subsequent exposures.

A pilot study to assess the hemostatic function of pathogen-reduced platelets in patients with thrombocytopenia

BACKGROUND

Platelet (PLT) support is critical to the care of patients with thrombocytopenia, but allogeneic transfusions carry risk. Pathogen reduction mitigates some transfusion risks, but effects on PLT function remain a concern. This clinical pilot study assessed the effect of pathogen reduction technology with riboflavin plus ultraviolet light using thrombelastography (TEG).

STUDY DESIGN AND METHODS

This prospective, randomized, crossover study compared Mirasol-treated (MIR) and standard reference (REF) PLT transfusions. PLT counts and TEG measurements were taken at pretransfusion and 1- and 24-hour-posttransfusion time points. The primary outcome measure was the pretransfusion to 1-hour-posttransfusion change in maximum amplitude (ΔMA(1 hr)). Secondary endpoints included ΔMA among other time points, relative MA, and the PLT count-MA correlation.

RESULTS

Of 16 enrolled patients, one withdrew before study treatment and three did not require two transfusions, leaving 12 patients in the efficacy analyses (seven MIR-REF, five REF-MIR). ΔMA(1 hr) (mean ± SD) was 10.60 ± 6.47 mm for MIR and 14.33 ± 5.38 mm for REF (p = 0.20, n = 10). ΔMA(24hr) was 9.49 ± 7.94 for MIR and 7.13 ± 3.08 for REF (p = 0.38, n = 9); ΔMA(24hr-1 hr) was -1.11 ± 2.95 for MIR and -7.20 ± 4.81 for REF (p = 0.016, n = 8). MA values for MIR and REF correlated with the log of PLT count (rMIR = 0.6901, rREF = 0.7399).

CONCLUSION

TEG is sensitive to changes in hemostatic function resulting from a single PLT transfusion. MIR and REF provided similar increments in hemostatic function in the immediate posttransfusion period and at 24 hours. A significant difference detected for ΔMA(24hr-1 hr) suggests different PLT clearance mechanisms. The relationship of these variables to clinically meaningful outcomes, for example, bleeding events or transfusion requirements, has yet to be determined.

Photochemical inactivation of chikungunya virus in plasma and platelets using the Mirasol pathogen reduction technology system

BACKGROUND

Chikungunya virus (CHIKV) is a reemerging mosquito-borne virus that has been responsible for a number of large-scale epidemics as well as imported cases covering a wide geographical range. As a blood-borne virus capable of mounting a high-titer viremia in infected humans, CHIKV was included on a list of risk agents for transfusion and organ transplant by the AABB Transfusion-Transmitted Diseases Committee. Therefore, we evaluated the ability of the Mirasol pathogen reduction technology (PRT) system (CaridianBCT Biotechnologies) to inactivate live virus in contaminated plasma and platelet (PLT) samples.

STUDY DESIGN AND METHODS

Plasma, PLTs, and phosphate-buffered saline controls were spiked with CHIKV and treated with riboflavin and varying doses of ultraviolet (UV) light using the Mirasol PRT system. Samples were tested before and after treatment for cytotoxicity, interference, and virus titer by titration and quantitative real-time reverse transcription-polymerase chain reaction.

RESULTS

A significant reduction in CHIKV titer of greater than 99% was recorded after treatment of plasma or PLTs with the Mirasol PRT system, and the titer reduction was directly proportional to the UV dose delivered to the samples. No cytotoxicity of interference was observed in any sample at any treatment dose.

CONCLUSION

These data indicate that the Mirasol PRT system efficiently inactivated live CHIKV in plasma and PLTs and could therefore potentially be used to prevent CHIKV transmission through the blood supply.

Preparation of cryoprecipitate from riboflavin and UV light-treated plasma

BACKGROUND AND OBJECTIVES

The Mirasol® pathogen reduction technology system for plasma is based on a riboflavin and UV light treatment process resulting in pathogen inactivation due to irreversible, photochemically induced damage of nucleic acids. This study was undertaken to evaluate the possibility of making pathogen reduced cryoprecipitate from riboflavin and UV light- treated plasma that meets the quality requirements specified by UK and European guidelines for untreated cryoprecipitate.

MATERIALS AND METHODS

Cryoprecipitate was made from riboflavin and UV light-treated plasma. Plasma units were thawed over a 20 h period at 4°C, and variable centrifugation settings (from 654 g for 2 min to 5316 g for 6 min) were applied to identify the optimal centrifugation condition. Plasma proteins in cryoprecipitate units were characterized on a STA Compact, Diagnostica STAGO and Siemens BCS analyzer.

RESULTS

Neither the centrifugation speed or time appeared to have an effect on the quality of the final cryoprecipitate product; however the initial solubilization of the cryoprecipitate product was found to be easier at the lower centrifugation setting (654 g for 2 min). Cryoprecipitate units prepared from Mirasol-treated plasma demonstrated protein levels that were less than levels in untreated products, but were on average 93 IU/unit, 262 mg/unit and 250 IU/unit for FVIII, fibrinogen and von Willebrand ristocetin cofactor activity, respectively.

CONCLUSION

Cryoprecipitate products prepared from Mirasol-treated plasma using a centrifugation method contain levels of fibrinogen, FVIII and von Willebrand ristocetin cofactor activity, that meet both the European and UK guidelines for untreated cryoprecipitate. Flexibility in centrifugation conditions should allow blood banks to use their established centrifugation settings to make cryoprecipitate from Mirasol-treated plasma.

[Pathogen reduction for platelets: available techniques and recent developments]

The will to reach for blood components a microbiological safety comparable to that of plasma-derived drugs led to the development of numerous pathogen reduction research programs for red blood cells and\or platelets in the 1990s. A consensus conference organized in 2007 allowed to define the main steps and precautions to be taken for the implementation of these processes. In the specific case of platelet concentrates, three processes stay this day in the run, even if they are not at the same development stage. A process using ultraviolet C only is at the stage of preclinical studies. The Mirasol® process, based on the activation of riboflavin by exposure to ultraviolet A and ultraviolet B is CE marked (class IIb), and a clinical study was published in 2010. The Intercept® process, involving the activation of a psoralen molecule by exposure to ultraviolet A, is CE marked (class III) since 2002, and has been licensed in France since 2005, in Germany since 2005 and in Switzerland since 2010. At least 12 clinical studies have been published. In regard to this last pathogen reduction process, the medical and scientific documentation, from in vitro investigations to post-marketing observational studies, is much more developed than the corresponding documentation of some innovative processes at the time of their generalization, such as the SAG-mannitol solution for red cell concentrates in 1979, leukoreduction filters for platelets and red cells concentrates in the 1990s, the solvent detergent therapeutic plasma in 1992 or the methylene blue therapeutic plasma in 2006.

A comparison of methods of pathogen inactivation of FFP

INTRODUCTION

Current methods for pathogen inactivation of plasma involve four major processes using solvent-detergent (SD), methylene blue (MB), amotosalen and riboflavin as additives. Three of these methods involve the use of visible or ultraviolet light.

METHODS

A comparison of the four methods was made using publications in Medline, Pubmed, Embase and Biosis to obtain data on the logistics of use, the quality of the plasma proteins and the effectiveness of pathogen inactivation.

RESULTS

Three of the methods, MB, amotosalen and riboflavin, are designed for use in a blood bank; the SD method is generally applied at a centralized manufacturing centre and involves large plasma pools. All methods result in a reduction in protein values with the per cent retention of FVIII activity in the range of 67-78% and fibrinogen of 65-84%. Protein S and alpha(2)-antiplasmin are lower following solvent-detergent treatment. Alterations in fibrinogen structure have been reported with methylene blue.

DISCUSSION

Three of the methods are designed for small volume use in a blood bank. All four methods have some effect on the coagulant proteins; however, the final concentrations are within regulated limits. While there is variability in the effectiveness against pathogens, direct comparison is difficult because of the methodologies used. Nonetheless, all are effective in inactivating HIV and other lipid-enveloped pathogens. Clinical studies on the effectiveness of these products are surprisingly sparse, and no randomized clinical trials have yet been performed with amotosalen or riboflavin plasmas.

Pathogen Reduction Technology Treatment of Platelets, Plasma and Whole Blood Using Riboflavin and UV Light

Bacterial contamination and emerging infections combined with increased international travel pose a great risk to the safety of the blood supply. Tests to detect the presence of infection in a donor have a 'window period' during which infections cannot be detected but the donor may be infectious. Agents and their transmission routes need to be recognized before specific tests can be developed. Pathogen reduction of blood components represents a means to address these concerns and is a proactive approach for the prevention of transfusion-transmitted diseases. The expectation of a pathogen reduction system is that it achieves high enough levels of pathogen reduction to reduce or prevent the likelihood of disease transmission while preserving adequate cell and protein quality. In addition the system needs to be non-toxic, non-mutagenic and should be simple to use. The Mirasol® Pathogen Reduction Technology (PRT) System for Platelets and Plasma uses riboflavin (vitamin B2) plus UV light to induce damage in nucleic acid-containing agents. The system has been shown to be effective against clinically relevant pathogens and inactivates leukocytes without significantly compromising the efficacy of the product or resulting in product loss. Riboflavin is a naturally occurring vitamin with a well-known and well-characterized safety profile. The same methodology is currently under development for the treatment of whole blood, making pathogen reduction of all blood products using one system achievable. This review gives an overview of the Mirasol PRT System, summarizing the mechanism of action, toxicology profile, pathogen reduction performance and clinical efficacy of the process.

White blood cell inactivation after treatment with riboflavin and ultraviolet light

Functional white blood cells (WBCs) in blood components may be responsible for a number of adverse transfusion effects, including transfusion-associated graft-versus-host disease (TA-GVHD), alloimmunization, and alloimmune platelet (PLT) refractoriness. TA-GVHD occurs when functional lymphocytes are transfused into a patient who is unable to mount an immune response to the human leukocyte antigen (HLA) due to HLA compatibility or immunosuppression. Alloantibodies against HLA antigens on donor WBCs and PLTs are the major cause of refractoriness to PLT transfusions in patients receiving repeated blood transfusions. Attempts to reduce these undesirable effects have included leukoreduction filters and gamma irradiation. Studies have shown that exposure of PLT concentrates to riboflavin and light (Mirasol pathogen reduction technology [PRT], CaridianBCT Biotechnologies) causes irreparable modifications of nucleic acids that result in inactivation of a wide range of pathogens as well as inhibition of the immunologic responses mediated by WBCs present in PLT concentrates. This article summarizes these studies and also reports on additional findings from the Trial to Reduce Alloimmunization to Platelets (TRAP) and Mirasol Clinical Evaluation (MIRACLE) trials. Data from in vitro studies and this clinical trial suggest that PRT treatment may be as effective as gamma irradiation in preventing TA-GVHD and more effective than leukoreduction in preventing alloimmunization.

The status of pathogen-reduced plasma

Efforts to reduce the risk of transfusion-transmitted infectious diseases began more than 4 decades ago with testing donated blood for syphilis. During the subsequent 4 decades, the number of recognized blood-borne transmissible agents and new laboratory tests has proliferated to a logistical breaking point. Further, the number of "emerging agents" which might enter the donor population is increasing continuously. In the search for an alternative to the laboratory testing strategy, pathogen-reduction technologies have emerged as the most promising. The model for this paradigm is pasteurization of a bottle of cow's milk. No matter what infective agent may be present in freshly collected cow's milk, pasteurization, i.e., a generic purification process can eliminate all potential infectivity, while preserving its essential biological properties--and an affordable cost. Several manufacturers have undertaken the challenge of developing a pathogen-reduction technology for blood components. Some novel technologies have proven successful for pooled plasma derivatives such as immune globulins, coagulation factor concentrate concentrates and albumin. The greatest challenge is finding a technology that is suitable for red blood cell and platelet components, whereas significant progress has been made already for pathogen-reduced plasma products. The present review addresses the status of implementation of pathogen-reduced plasma products in the global market. Some blood centers and hospital blood banks in Europe and the Middle East have begun to distribute pathogen-reduced plasma, but no pathogen-reduced plasma product is presently approved by the US Food and Drug Administration. While many observers in the United States focus on the regulatory process as the impediment to widespread implementation, the real challenge will be paying the surcharge for the pathogen-reduction process - an as yet unspecified figure - but likely to add a very substantial amount to the annual healthcare budget.

Evaluation of the Mirasol pathogen [corrected] reduction technology system against Babesia microti in apheresis platelets and plasma

BACKGROUND

Babesia microti is an intraerythrocytic parasite, transmitted naturally to humans by infected ixodid ticks, that causes babesiosis. In recent years, B. microti has been identified as a growing public health concern that has also emerged as a critical blood safety issue in the absence of appropriate interventions to reduce transmission by blood transfusion. Thus, we evaluated the ability of the Mirasol pathogen reduction technology (PRT; CaridianBCT), which uses riboflavin (RB) and ultraviolet (UV) light, to diminish the presence of B. microti in apheresis plasma and platelets (PLTs).

STUDY DESIGN AND METHODS

Apheresis plasma and PLT units were spiked with B. microti-infected hamster blood and subsequently treated using the Mirasol PRT system. Control and experimental samples were collected at different stages during the treatment process and injected into hamsters to detect the presence of viable parasites. Four weeks postinoculation, hamster blood was tested for B. microti infection by blood smear and real-time polymerase chain reaction analysis.

RESULTS

None of the blood smears from animals injected with samples from PRT-treated plasma or PLT units were positive by microscopy, while all the non-PRT-treated plasma and PLT units were demonstrably parasitemic. Parasite load reduction in hamsters ranged between 4 and 5 log in all PRT-treated units compared to untreated controls.

CONCLUSION

The data indicate that the use of RB and UV light efficiently reduces the presence of viable B. microti in apheresis plasma and PLT products, thereby reducing the risk of transfusion-transmitted Babesia potentially associated with these products. Based on this observed "proof of principle," future studies will determine the efficacy of the Mirasol PRT in whole blood.

Emerging infectious disease agents and their potential threat to transfusion safety

BACKGROUND

Emerging infections have been identified as a continuing threat to human health. Many such infections are known to be transmissible by blood transfusion, while others have properties indicating this potential. There has been no comprehensive review of such infectious agents and their threat to transfusion recipient safety to date.

STUDY DESIGN AND METHODS

The members of AABB's Transfusion Transmitted Diseases Committee reviewed a large number of information sources in order to identify infectious agents with actual or potential risk of transfusion transmission now or in the future in the US or Canada; with few exceptions, these agents do not have available interventions to reduce the risk of such transmission. Using a group discussion and writing process, key characteristics of each agent were identified, researched, recorded and documented in standardized format. A group process was used to prioritize each agent on the basis of scientific/epidemiologic data and a subjective assessment of public perception and/or concern expressed by regulatory agencies.

RESULTS

Sixty-eight infectious agents were identified and are described in detail in a single Supplement to TRANSFUSION. Key information will also be provided in web-based form and updated as necessary. The highest priorities were assigned to Babesia species, Dengue virus, and vCJD.

CONCLUSION

The information is expected to support the needs of clinicians and transfusion medicine experts in the recognition and management of emerging infections among blood donors and blood recipients.

Understanding loss of donor white blood cell immunogenicity after pathogen reduction: mechanisms of action in ultraviolet illumination and riboflavin treatment

BACKGROUND

Donor white blood cells (WBCs) present in transfusion products can lead to immune sequelae such as production of HLA antibodies or graft-versus-host disease in susceptible transfusion recipients. Eliminating the immunogenicity of blood products may prove to be of clinical benefit, particularly in patients requiring multiple transfusions in whom allosensitization is common. This study examines a method of pathogen reduction based on ultraviolet light illumination in the presence of riboflavin. In addition to pathogens, WBCs treated with this system are affected and fail to stimulate proliferation of allogeneic peripheral blood mononuclear cells (PBMNCs) in vitro.

STUDY DESIGN AND METHODS

This study sought to determine the mechanisms regulating this loss of immunogenicity. Treated cells were examined for surface expression of a number of molecules involved in activation and adhesion, viability, cell-cell conjugation, and ability to stimulate immune responses in allogeneic PBMNCs.

RESULTS

Compared with untreated controls, ultraviolet (UV)-irradiated antigen-presenting cells showed slightly reduced surface expression of HLA Class II and costimulatory molecules and had more significant reductions in surface expression of a number of adhesion molecules. Furthermore, treated cells had a severe defect in cell-cell conjugation. The observed loss of immunogenicity was nearly complete, with UV-irradiated cells stimulating barely measurable interferon-gamma production and no detectable STAT-3, STAT-5, or CD3-epsilon phosphorylation in allospecific primed T cells.

CONCLUSION

These results suggest that defective cell-cell adhesion prevents UV-irradiated cells from inducing T-cell activation.

[Evolution of techniques for preparation of labile blood products (LBP): pathogen inactivation in LBP]

The techniques for inactivation of pathogens in labile blood products (LBP) would appear to be the new strategy which will permit us to increase transfusion safety in the face of the risks of transmission of pathogenic agents by LBP. Various methods are in the course of development or already validated and used in France. The latter only apply however to plasma or platelet concentrates. The mechanisms of action and the efficacy of inactivation and attenuation of pathogenic agents vary with the different techniques. Each of these constitutes a preparative procedure composed of unit steps which have to be fully mastered in order to ensure the quality and transfusion efficacy of the treated product.