Direct assessment of cytomegalovirus transfusion-transmitted risks after universal leukoreduction

A novel multiplex real-time PCR assay for the detection of cytomegalovirus, Epstein-Barr virus, herpes simplex virus 1/2 and strategies for application to blood screening

A multiplex real-time PCR has been developed to simultaneously detect transfusion-transmissible pathogens cytomegalovirus, Epstein-Barr virus and herpes simplex virus, as well as to provide sample quality testing, for the conserved regions of the cytomegalovirus UL123 gene, the Epstein-Barr virus BKRF1 gene, and the herpes simplex virus 1/2 UL30 gene, tested on 500 blood donors and 320 transfusion recipients. The laboratory sensitivities for all 3 pathogens were 100 copies/μL. Compared to the commercial real-time PCR reference kit, the multiplex real-time PCR assay for the detection of CMV, EBV and HSV presented 100% consistency. In 820 whole blood samples, the multiplex real-time PCR assay identified 34 (4.15%) positive for CMV DNA, 15 (1.83%) positive for EBV DNA, and 6 (0.73%) positive for HSV DNA. For blood transfusions in high-risk groups, whole blood herpes virus test should be included in the spectrum of pathogen testing for blood donors and recipients.

Blood Product (Donor) Noninfectious and Infectious Testing and Modification

Blood transfusion begins with safe donor selection and testing. In the United States, the blood supply and transfusion are highly regulated. Blood transfusion safety is multifaceted, whereby each of the elements of the blood safety value chain, spanning donor recruitment and qualification, to collection, blood processing, testing, transfusion practice, and posttransfusion surveillance, must be optimized to minimize risk. Pathogen inactivation is a promising approach to decrease bacterial contamination of platelets, inactivate parasites and viruses, and decrease risks associated with emerging and unidentified pathogens. This article offers an overview of blood donor infectious and noninfectious testing in the United States.

Cytomegalovirus seroprevalence among blood donors: a systematic review and meta-analysis

Background

Screening for cytomegalovirus (CMV)-specific antibodies is not routine in some settings. Thus, transfusion of blood products poses risks for susceptible individuals.

Objectives

To investigate the global pooled CMV seroprevalence among volunteer blood donors.

Methods

This systematic review and meta-analysis was performed according to PRISMA guidelines. The databases searched included Embase, Google Scholar, Medline, PubMed, Web of Science, and Cochrane Library. Data were extracted independently and analyzed using STATA version 11.

Results

The global seroprevalence of CMV IgG, CMV IgM, and both CMV IgM and IgG was 83.16% (95% confidence interval [CI]: 78.55–87.77%, I² = 99.5%), 13.77% (95% CI: 11.59–15.95%, I² = 98.8%), and 23.78% (95% CI: 10.50–37.06%, I² = 98.7), respectively.

Conclusion

The global seroprevalence of CMV was high among blood donors. Therefore, regular CMV screening should be conducted to identify CMV-seronegative blood donors.

Inactivation of a broad spectrum of viruses and parasites by photochemical treatment of plasma and platelets using amotosalen and ultraviolet A light

BACKGROUND

The INTERCEPT Blood System pathogen reduction technology (PRT), which uses amotosalen and ultraviolet A light treatment (amotosalen/UV-PRT), inactivates pathogens in plasma and platelet components (PCs). This review summarizes data describing the inactivation efficacy of amotosalen/UVA-PRT for a broad spectrum of viruses and parasites.

METHODS

Twenty-five enveloped viruses, six nonenveloped viruses (NEVs), and four parasites species were evaluated for sensitivity to amotosalen/UVA-PRT. Pathogens were spiked into plasma and PC at high titers. Samples were collected before and after PRT and assessed for infectivity with cell cultures or animal models. Log reduction factors (LRFs) were defined as the difference in infectious titers before and after amotosalen/UV-PRT.

RESULTS

LRFs of ≥4.0 log were reported for 19 pathogens in plasma (range, ≥4.0 to ≥7.6), 28 pathogens in PC in platelet additive solution (PC-PAS; ≥4.1-≥7.8), and 14 pathogens in PC in 100% plasma (PC-100%; (≥4.3->8.4). Twenty-five enveloped viruses and two NEVs were sensitive to amotosalen/UV-PRT; LRF ranged from >2.9 to ≥7.6 in plasma, 2.4 or greater to greater than 6.9 in PC-PAS and >3.5 to >6.5 in PC-100%. Infectious titers for four parasites were reduced by >4.0 log in all PC and plasma (≥4.9 to >8.4).

CONCLUSION

Amotosalen/UVA-PRT demonstrated effective infectious titer reduction for a broad spectrum of viruses and parasites. This confirms the capacity of this system to reduce the risk of viral and parasitic transfusion-transmitted infections by plasma and PCs in various geographies.

Transfusion-transmitted cytomegalovirus: behaviour of cell-free virus during blood component processing. A study on the safety of labile blood components in Switzerland

BACKGROUND

Nowadays, most blood products are leukocyte-reduced. After this procedure, the residual risk for transfusion transmitted cytomegalovirus (TT-CMV) is mostly attributed to cell-free viruses in the plasma of blood donors following primary infection or viral reactivation. Here, objectives are: 1) to study the behaviour of cell-free CMV through the blood component processing; 2) to determine the anti-CMV seroprevalence, the level of viremia, the window-period in blood donor population; and 3) to identify cases of TT-CMV in bone marrow transplant (BMT) recipients.

MATERIALS AND METHODS

Cell-free CMV was injected into blood bags originating from regular donors. Blood components were processed according to either the CompoSelect^® or the CompoFlow^® (Fresenius Kabi AG) techniques. Samples were analysed at each step for presence of virus DNA using quantitative polymerase chain reaction (PCR). The anti-CMV seroprevalence in our donor population was taken from our donor data system. The viremia was assessed in pooled plasmas samples from routine donations by quantitative PCR. Medical charts of 165 BMT anti-CMV seronegative recipients/anti-CMV seronegative donors who received CMV-unscreened blood products were reviewed.

RESULTS

Cell-free CMV passes without any decrease in viral load through all stages of blood processing. The anti-CMV seroprevalence was 46.13%. Four DNA positive samples out of 42,240 individual blood donations were identified (0.009%); all had low levels of viremia (range 11-255 IU/mL). No window-period donation was identified. No TT-CMV was found.

DISCUSSION

Cell-free CMV remains a concern with current blood component processing as it passes through all the processes. However, since low levels of CMV DNA were identified in the donations tested, and no BMT recipients had TT-CMV, the residual threat of TT-CMV after leukocyte reduction appears to be very low.

Risk of cytomegalovirus transmission by blood products after solid organ transplantation

Cytomegalovirus (CMV) infection and CMV disease are significant contributors to increased morbidity, mortality, and cost for immunocompromised solid organ transplant recipients. Although the most significant risk for CMV transmission is the CMV serological status of the transplant donor and recipient, exposure to blood products is another potential risk factor. Before the era of leukocyte reduction, CMV seronegative products were issued to reduce the risk of CMV transmission, thus rendering the products CMV safe. This approach requires maintenance of two inventories of blood products and continuous donor testing. Leukocyte-reduced cellular transfusion products are also considered CMV safe and are essentially universally available. To minimize the risk of CMV infection in transplant recipients, strategies include use of seronegative blood products or prestorage leukocyte reduction. However, no recent randomized prospective controlled trial directly compares the two CMV safety approaches for transplant recipients. Hence, current policy relies on historic trials and more recent observational studies. As a consequence, though generally considered equivalent approaches, preferred practice varies between centers. This review provides guidance to inform an acceptable practice approach.

Transfusion of pathogen-reduced platelet components without leukoreduction

BACKGROUND

Leukoreduction (LR) of platelet concentrate (PC) has evolved as the standard to mitigate risks of alloimmunization, clinical refractoriness, acute transfusion reactions (ATRs), and cytomegalovirus infection, but does not prevent transfusion-associated graft-versus-host disease (TA-GVHD). Amotosalen-ultraviolet A pathogen reduction (A-PR) of PC reduces risk of transfusion-transmitted infection and TA-GVHD. In vitro data indicate that A-PR effectively inactivates WBCs and infectious pathogens.

STUDY DESIGN AND METHODS

A sequential cohort study evaluated A-PR without LR, gamma irradiation, and bacterial screening in hematopoietic stem cell transplant (HSCT) recipients. The first cohort received conventional PC (control) processed without LR, but with gamma irradiation and bacterial screening. The second cohort received A-PR PC (test) processed without: LR, bacterial screening, or gamma irradiation. The primary efficacy outcome was the 1-hour corrected count increment. The primary safety outcome was treatment-emergent ATR. Secondary outcomes included clinical refractoriness, and 100-day status for engraftment, TA-GVHD, HSCT-GVHD, infections, and mortality.

RESULTS

Mean corrected count increment (× 10³ ) of 33 test PC recipients was similar (18.9 ± 8.8 vs. 16.6 ± 8.4; p = 0.296) to that of 31 control PC recipients. Test recipients had a reduced, but nonsignificant, incidence of ATR (test = 9.1%, Control = 19.4%; p = 0.296). The frequencies of clinical refractoriness (0 of 33 vs. 4 of 31 patients) and refractory transfusions (6.6% vs. 19.3%) were lower in the test cohort (p = 0.05 and 0.02), respectively. No patient in either cohort had TA-GVHD. Day 100 engraftment, HSCT-GVHD, mortality, and infectious disease complications were similar between cohorts.

CONCLUSIONS

This study indicated that A-PR PC without LR, gamma irradiation, or bacterial screening is feasible for support of HSCT.

Human cytomegalovirus haplotype reconstruction reveals high diversity due to superinfection and evidence of within-host recombination

Human cytomegalovirus (HCMV) is a major global cause of congenital disability and transplant-related morbidity. Excessive levels of within-host HCMV nucleotide diversity are attributed to unexpectedly high mutation rates. Here, we show that high HCMV diversity is due to the frequent presence of mixed infections with genetically distinct strains, whereas HCMV in nonmixed infections is no more diverse than other DNA viruses. Using serial patient samples, we reconstruct viral strain haplotypes to pinpoint the timing of HCMV superinfections occurring within the study sampling time frame and uncover within-host viral recombination. From these results, we identify likely sources of infection and demonstrate probable selection for recombinant viruses. These results generate new, yet testable, insights into putative viral and host drivers of HCMV evolution and pathogenesis.

Recent sequencing efforts have led to estimates of human cytomegalovirus (HCMV) genome-wide intrahost diversity that rival those of persistent RNA viruses [Renzette N, Bhattacharjee B, Jensen JD, Gibson L, Kowalik TF (2011) PLoS Pathog 7:e1001344]. Here, we deep sequence HCMV genomes recovered from single and longitudinally collected blood samples from immunocompromised children to show that the observations of high within-host HCMV nucleotide diversity are explained by the frequent occurrence of mixed infections caused by genetically distant strains. To confirm this finding, we reconstructed within-host viral haplotypes from short-read sequence data. We verify that within-host HCMV nucleotide diversity in unmixed infections is no greater than that of other DNA viruses analyzed by the same sequencing and bioinformatic methods and considerably less than that of human immunodeficiency and hepatitis C viruses. By resolving individual viral haplotypes within patients, we reconstruct the timing, likely origins, and natural history of superinfecting strains. We uncover evidence for within-host recombination between genetically distinct HCMV strains, observing the loss of the parental virus containing the nonrecombinant fragment. The data suggest selection for strains containing the recombinant fragment, generating testable hypotheses about HCMV evolution and pathogenesis. These results highlight that high HCMV diversity present in some samples is caused by coinfection with multiple distinct strains and provide reassurance that within the host diversity for single-strain HCMV infections is no greater than for other herpesviruses.

Interleukin-8, interleukin-1β and tumour necrosis factor-α in sequential units of packed red blood cells collected from retired racing Greyhounds

BACKGROUND

We hypothesised that concentrations of interleukin-8 (IL-8), interleukin-1β (IL-1β) and tumour necrosis factor-α (TNF-α) would increase during storage in the third sequential unit (U3) of canine packed red blood cells (PRBC) collected from terminal donors in haemorrhagic shock. We further hypothesised that leucoreduction would prevent cytokine accumulation in U3 and that cytokine concentrations in U3 would be higher than in the first units (U1) collected from the same dogs.

METHODS

U1 and U3 were each collected from 12 anaesthetised healthy Greyhounds. Removal of leucocytes from half of each PRBC unit produced one leucoreduced (LR) and one non-leucoreduced (NLR) unit. Canine IL-8, IL-1β and TNF-α concentrations were measured in samples collected from the units during storage on days 0, 10, 20, 30 and 37.

RESULTS

The IL-8 concentration in U3 NLR units was significantly higher on days 10, 20, 30 and 37 than on day 0 and was significantly higher than in the LR units at all time points. The IL-1β concentration in U3 did not change over time, or between LR and NLR units. TNF-α was not detected in any unit. There were no significant differences in IL-8 or IL-1β concentrations between U3 and U1 at any time point; however, some NLR U3 units had markedly elevated IL-8 concentrations at day 37 (2060-20,682 pg/mL) compared with NLR U1 units (3369-5280 pg/mL).

CONCLUSION

NLR U3 units collected from dogs in haemorrhagic shock showed a significant increase in IL-8 concentrations during storage. Leucoreduction was effective at preventing the accumulation of IL-8. There was no difference detected between U3 and U1.

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.

Provision of cellular blood components to CMV-seronegative patients undergoing allogeneic stem cell transplantation in the UK: survey of UK transplant centres

OBJECTIVES

To identify current UK practice with regards to provision of blood components for cytomegalovirus (CMV)-seronegative, potential, allogeneic stem cell recipients of seronegative grafts.

BACKGROUND

Infection with CMV remains a major cause of morbidity and mortality after allogeneic stem cell transplantation (aSCT). CMV transmission has been a risk associated with the transfusion of blood components from previously exposed donors, but leucocyte reduction has been demonstrated to minimise this risk. In 2012, the UK Advisory Committee for the Safety of Tissues and Organs (SaBTO) recommended that CMV-unselected components could be safely transfused without increased risk of CMV transmission.

METHODS

We surveyed UK aSCT centres to establish current practice.

RESULTS

Fifteen adult and seven paediatric centres (75%) responded; 22·7% continue to provide components from CMV-seronegative donors. Reasons cited include the continued perceived risk of CMV transmission by blood transfusion, its associated morbidity and concerns regarding potential for ambiguous CMV serostatus in seronegative potential transplant recipients due to passive antibody transfer from CMV-seropositive blood donors, leading to erroneous donor/recipient CMV matching at transplant.

CONCLUSIONS

The survey demonstrated a surprisingly high rate (22.7%) of centres continuing to provide blood components from CMV-seronegative donors despite SaBTO guidance.

Survey on Transfusion-Transmitted Cytomegalovirus and Cytomegalovirus Disease Mitigation

CONTEXT

- Cytomegalovirus (CMV) can be transmitted by cellular blood products, leading to severe disease in immunosuppressed patients such as neonates and transplant recipients. To mitigate transfusion-transmitted CMV (TT-CMV), "CMV-safe" blood products (leukoreduced and/or CMV-seronegative) are transfused. Attempts to develop practice guidelines for TT-CMV mitigation have been limited by paucity of high-quality clinical trials.

OBJECTIVE

- To assess current TT-CMV mitigation strategies across medical institutions for specific at-risk populations.

DESIGN

- Supplemental questions regarding TT-CMV and CMV disease mitigation were added to a College of American Pathologists Transfusion Medicine (Comprehensive) Participant Survey in 2015, addressing whether a given institution provided CMV-safe products for 6 at-risk patient populations.

RESULTS

- Ninety percent (2712 of 3032) of institutions reported providing universally leukoreduced blood products. Among institutions without universal leukoreduction, 92% (295 of 320) provided leukoreduced products on the basis of clinical criteria. Eighty-three percent (2481 of 3004) of respondents reported having availability of CMV-seronegative products; however, wide variation in policies was reported governing CMV-seronegative product use. Among all respondents, less than 5% reported using CMV prophylaxis and monitoring in high-risk patient groups. Transplant centers reported higher rates of CMV prophylaxis (25% [97 of 394] solid organ) and monitoring (15% [59 of 394] solid organ) for CMV-negative transplant recipients.

CONCLUSIONS

- Universal leukoreduction is the primary strategy for mitigating TT-CMV. While most institutions have both CMV-seronegative and leukoreduced blood products available, consensus is lacking on which patients should receive these products. High-quality studies are needed to determine if CMV-seronegative and leukoreduced blood products are needed in high-risk patient populations.

Transfusion-transmitted CMV infection - current knowledge and future perspectives

Transmission of human cytomegalovirus (CMV) via transfusion (TT-CMV) may still occur and remains a challenge in the treatment of immunocompromised CMV-seronegative patients, e.g. after stem cell transplantation, and for low birthweight infants. Measures to reduce the risk of TT-CMV have been evaluated in clinical studies, including leucocyte depletion of cellular blood products and/or the selection of CMV-IgG-negative donations. Studies in large blood donor cohorts indicate that donations from newly CMV-IgG-positive donors should bear the highest risk for transmitting CMV infections because they contain the highest levels of CMV-DNA, and early CMV antibodies cannot neutralise CMV. Based on this knowledge, rational strategies to reduce the residual risk of TT-CMV using leucoreduced blood products could be designed. However, there is a lack of evidence that CMV is still transmitted by transfusion of leucoreduced units. In low birthweight infants, most (if not all) CMV infections are caused by breast milk feeding or congenital transmission rather than by transfusion of leucoreduced blood products. For other patients at risk, no definitive data exist about the relative importance of alternative transmission routes of CMV compared to blood transfusion. As a result, only the conduction of well-designed studies addressing strategies to prevent TT-CMV and the thorough examination of presumed cases of TT-CMV will achieve guidance for the best transfusion regimen in patients at risk.

Survey of Institutional Policies for Provision of "CMV-Safe" Blood in Ontario

OBJECTIVES

Debate continues on whether leukoreduction alone (LR) is sufficiently similar to leukoreduced cellular products drawn from cytomegalovirus (CMV)-seronegative (SN) donors to minimize the risk of transfusion-transmitted CMV (TT-CMV). We sought to determine the policy, inventory, and practice landscape of the province for TT-CMV mitigation.

METHODS

A web-based survey was distributed to hospitals in Ontario by Canadian Blood Services to collect data on their policies with respect to TT-CMV prevention.

RESULTS

TT-CMV mitigation practices varied by patient population, hospital size, and region. Smaller institutions remain committed to dual prevention, whereas academic hospitals favor a single-measure approach. Although smaller institutions attempt to align their policies with leadership sites, emulation is often inaccurate. The demands for SN products also appear to be significantly lower than the current screening practices of Canadian Blood Services.

CONCLUSIONS

Standardization is lacking on practices to prevent TT-CMV. Although there are barriers to harmonizing practices, the apparent shift to policies acknowledging LR as a sufficient protection is likely to continue.

Effect of leukoreduction on concentrations of interleukin-8, interleukin-1β, and tumor necrosis factor-α in canine packed red blood cells during storage

OBJECTIVE To measure changes in interleukin-8 (IL-8), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) concentrations in stored canine packed RBCs (PRBCs) over time and assess the effect of leukoreduction on these cytokine concentrations. ANIMALS 12 anesthetized healthy Greyhounds. PROCEDURES 1 unit of whole blood from each dog was processed into PRBCs. Half of each PRBCs unit was passed through a leukoreduction filter to produce a leukoreduced unit, and the remaining blood was kept as a nonleukoreduced unit. All units had a CBC performed on day 0 (day of collection) and were stored at 2° to 6°C. Samples were collected from leukoreduced and nonleukoreduced units on days 0, 10, 20, 30, and 37 and centrifuged; the supernatant was stored at -80°C until analysis. Canine TNF-α and IL-8 concentrations were assessed with a multiplexed genomic and proteomic biomarker analyzer, and canine IL-1β concentration was measured by ELISA. RESULTS Leukocyte counts were decreased by ≥ 99.9% in all leukoreduced units. Median TNF-α and IL-1β concentrations were not significantly different between leukoreduced and nonleukoreduced units and did not change significantly during storage; median IL-8 concentration was significantly higher in nonleukoreduced versus leukoreduced units on all days, and was greater at all time points after ≥ 10 days of storage than on day 0. Median IL-8 concentration in leukoreduced units did not increase during storage. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that leukoreduction was effective for the removal of leukocytes from canine PRBCs and prevented significant increases in IL-8 concentration during storage. Further studies are needed to evaluate whether leukoreduction reduces cytokine-associated complications of transfusion.

Postnatal cytomegalovirus infection: a pilot comparative effectiveness study of transfusion safety using leukoreduced-only transfusion strategy

BACKGROUND

The optimal mitigation strategy to prevent transfusion transmission of cytomegalovirus (TT-CMV) in preterm very low birthweight infants remains debated. Hospitals caring for this patient population have varied practices.

STUDY DESIGN AND METHODS

A prospective observational comparative effectiveness pilot study was conducted to determine the feasibility for a larger study. The pilot was carried out at hospitals using a leukoreduction (LR)-only transfusion strategy. Specimen and data collection for this study was performed in a similar approach to a study completed at Emory University that employed the CMV-seronegative plus LR approach. All testing was performed at one laboratory. The rates of TT-CMV using the two transfusion strategies were compared.

RESULTS

Zero incidence of TT-CMV was detected in infants (n = 20) transfused with LR-only blood (0/8; 95% confidence interval [CI], 0-25.3%) and is consistent with the previously reported zero incidence of TT-CMV finding in a cohort of infants transfused with CMV-negative plus LR blood (0/310; 95% CI, 0%-0.9%). The seroprevalence rate among enrolled mothers (n = 17) was 60%. Forty percent of those infants (8/20) received 43 transfusions; five were transfused with one or more CMV-seropositive blood components. One infant had tested positive for CMV before receiving blood transfusions; the infant's mother was CMV immunoglobulin (Ig)G positive and IgM negative.

CONCLUSIONS

Using the LR-only transfusion approach, zero cases of TT-CMV were detected in this pilot study. A larger study is needed to reliably determine the most effective strategy for prevention of TT-CMV in this population.

Sequence analysis of two variable cytomegalovirus genes for distinction between transfusion- and breast milk-transmitted infections in a very-low-birthweight infant

BACKGROUND

Cytomegalovirus (CMV) infections in very-low-birthweight infants can lead to serious clinical consequences. When CMV-related symptoms occur after transfusion, CMV transmission is often attributed to the transfusion products rather than to breast milk. However, it is sometimes difficult to distinguish between transfusion-transmitted and breast milk-transmitted CMV infections.

PATIENT AND METHODS

A patient was born at 27 gestational weeks with a weight of 689 g. He was transfused with leukoreduced red blood cells (LR-RBCs), which were later found to be CMV seropositive and CMV DNA positive. He was also fed with CMV DNA-positive breast milk. Thereafter, he developed CMV disease with thrombocytopenia and jaundice. To determine the route of transmission, we analyzed the sequences of two variable CMV genes, UL139 and UL146, by direct sequence analysis. We also performed deep sequence analysis to determine whether there were polyclonal CMV strains in the LR-RBCs transfused.

RESULTS

CMV DNA sequence-matching rates for the LR-RBCs and the patient's blood were 64.6% for the UL139 gene and 68.6% for the UL146 gene. In contrast, the sequences of these genes in the patient's blood were 100% matched with those in the breast milk. Furthermore, by deep sequence analysis, the CMV strain found in the patient's blood was not detected in the LR-RBCs transfused.

CONCLUSION

The results indicate that the pathogenic CMV strain was transmitted through breast milk, which is consistent with the claims that transfusion-transmitted CMV infection due to leukoreduced blood products is uncommon.

Leucoreduction of blood components: an effective way to increase blood safety?

Over the past 30 years, it has been demonstrated that removal of white blood cells from blood components is effective in preventing some adverse reactions such as febrile non-haemolytic transfusion reactions, immunisation against human leucocyte antigens and human platelet antigens, and transmission of cytomegalovirus. In this review we discuss indications for leucoreduction and classify them into three categories: evidence-based indications for which the clinical efficacy is proven, indications based on the analysis of observational clinical studies with very consistent results and indications for which the clinical efficacy is partial or unproven.

Risks associated with red blood cell transfusions: potential benefits from application of pathogen inactivation

BACKGROUND

Red blood cell (RBC) transfusion risks could be reduced if a robust technology for pathogen inactivation of RBC (PI-RBCs) were to be approved.

MATERIALS AND METHODS

Estimates of per-unit and per-patient aggregate infectious risks for conventional RBCs were calculated; the latter used patient diagnosis as a determinant of estimated lifetime exposure to RBC units. Existing in vitro data for the two technologies under development for producing PI-RBCs and the status of current clinical trials are reviewed.

RESULTS

Minimum and maximum per-unit risk were calculated as 0.0003% (1 in 323,000) and 0.12% (1 in 831), respectively. The minimum estimate is for known lower-risk pathogens while the maximal estimate also includes an emerging infectious agent (EIA) and endemic area Babesia risk. Minimum and maximum per-patient lifetime risks by diagnosis grouping were estimated as 1.5 and 3.3%, respectively, for stem cell transplantation (which includes additional risk for cytomegalovirus transmission); 1.2 and 3.7%, respectively, for myelodysplastic syndrome; and 0.2 and 44%, respectively, for hemoglobinopathy.

DISCUSSION

There is potential for PI technologies to reduce infectious RBC risk and to provide additional benefits (e.g., prevention of transfusion-associated graft-versus-host disease and possible reduction of alloimmunization) due to white blood cell inactivation. PI-RBCs should be viewed in the context of having a fully PI-treated blood supply, enabling a blood safety paradigm shift from reactive to proactive. Providing insurance against new EIAs. Further, when approved, the use of PI for all components may catalyze operational changes in blood donor screening, laboratory testing, and component manufacturing.

Transfusion in CMV seronegative T-depleted allogeneic stem cell transplant recipients with CMV-unselected blood components results in zero CMV transmissions in the era of universal leukocyte reduction: a U.K. dual centre experience

OBJECTIVES

To establish rates of cytomegalovirus (CMV) transmission with use of CMV-unselected (CMV-U), leukocyte-reduced blood components transfused to CMV-seronegative patient/CMV-seronegative donor (CMV neg/neg) allogeneic stem cell transplantation (SCT) recipients including those receiving T-depleted grafts.

BACKGROUND

CMV infection remains a major cause of morbidity following SCT. CMV-seronegative SCT recipients are particularly at risk of transfusion transmitted CMV (TT-CMV) and until recently they have received blood components from CMV-seronegative donors with significant resource implications. Although leukocyte reduction of blood components is reported to minimise risk of TT-CMV, its efficacy in high-risk situations, such as in T-depleted transplant recipients, is unknown.

METHODS

We retrospectively analysed the incidence of TT-CMV in CMV neg/neg allogeneic SCT recipients transfused with CMV-U, leukocyte-reduced blood components in two transplantation centres in the UK. Patients were monitored for CMV infection by weekly CMV polymerase chain reaction testing. Leukocyte reduction of blood components was in accordance with current UK standards.

RESULTS

Among 76 patients, including 59 receiving in vivo T-depletion, no episodes of CMV infection were detected. Patients were transfused with 1442 CMV-unselected, leukocyte-reduced components, equating to 1862 donor exposures.

CONCLUSIONS

Our findings confirm the safety of leukocyte reduction as a strategy in preventing TT-CMV in high-risk allogeneic SCT recipients.

Red blood cell transfusions for thalassemia: results of a survey assessing current practice and proposal of evidence-based guidelines

BACKGROUND

In the absence of curative treatment, such as stem cell transplant, regular transfusions remain the mainstay of therapy for individuals with thalassemia major, a syndrome that results from marked ineffective erythropoiesis and the resultant anemia. The primary objectives of transfusion therapy are twofold: to suppress ineffective erythropoiesis and to ensure appropriate growth and development through childhood. In practice, a number of different transfusion protocols are in use across the developed world, with on-demand transfusion still being the paradigm in most of the developing world with limited resources.

STUDY DESIGN AND METHODS

To investigate perceived differences in transfusion practice, a self-reported electronic survey was disseminated to eight US thalassemia treatment centers in February 2011. The survey was divided into sections ranging from laboratory and clinical practices to emerging transfusion-transmitted diseases.

RESULTS

The survey response rate was 100%. The total number of transfused patients was 411. One-hundred percent of institutions used leukoreduced blood. No centers routinely provided cytomegalovirus-seronegative red blood cells (RBCs). Half the centers provided irradiated RBCs; only one routinely provided washed RBCs, and none transfused RBCs of defined storage age. Seventy-five percent of centers routinely phenotyped thalassemia patients' RBC antigens; 50% prophylactically matched for Rh and K antigens. The frequency of antibody investigations varied widely, and 25% of centers routinely medicated patients before transfusion.

CONCLUSION

Eight thalassemia centers in the United States were surveyed to determine the uniformity of transfusion practice. The variability of the results was surprising. Consequently, we performed a literature review and propose an evidence-based protocol for routine transfusion therapy for patients with thalassemia.

Prevention of Transfusion-Transmitted Cytomegalovirus Infections: Which is the Optimal Strategy?

Traditionally, leukoreduction and selection of blood products from seronegative donors have been used as alternative strategies to reduce the risk of transfusion-transmitted cytomegalovirus infections (TT-CMV) in atrisk patients. After the introduction of universal leukoreduction for red blood cell and platelet concentrates in Germany, a controversy evolved as to whether the additional selection of blood products from seronegative donors would reduce or even increase the risk of TT-CMV. This review summarizes the current knowledge about CMV infections in blood donors and the implications of this information on the effect of potential transfusion strategies. Even though there are conflicting data about the incidence of TT-CMV remaining after the introduction of leukodepletion, it has been clearly shown that both prevalence and concentration of CMV DNA in peripheral blood are highest in newly seropositive donors. Therefore, avoidance of blood products from these donors is the most important goal of any transfusion strategy. This goal can be reached by: i) selection of blood products from seronegative donors, ii) provision of CMV DNA-negative blood products, or iii) provision of blood from long-term seropositive donors. In cases of suspected TT-CMV, all implicated donors should be investigated carefully to gather further knowledge on which donors confer the lowest risk for TT-CMV.

The impact of donor cytomegalovirus DNA on transfusion strategies for at-risk patients

BACKGROUND

Cytomegalovirus (CMV) DNA is frequently detected in plasma of newly seropositive donors. Selection of leukoreduced blood products from donors with remote CMV infection could avoid transfusion-transmitted CMV infections (TT-CMV) due to primarily infected donors. However, there are no data about the prevalence of reactivations in long-term seropositive donors compared to the incidence of window period donations in seronegative donors. Therefore, the optimal transfusion strategy for at-risk patients is unclear.

STUDY DESIGN AND METHODS

Whole blood samples from 22,904 donations were tested for CMV DNA, and CMV DNA-positive donations were categorized as donations from 1) seronegative donors, 2) newly seropositive donors, and 3) long-term seropositive donors.

RESULTS

Twenty-one donors were reproducibly CMV DNA-positive (0.09%). Frequency of detection and concentration of CMV DNA in whole blood were comparable for seronegative and long-term seropositive donors. Nonreproducibly positive results for CMV DNA in whole blood were more frequent in long-term seropositive donors (0.16% vs. 0.01%, p<0.01). Only low concentrations of CMV DNA in plasma were detectable in two seronegative donors and one long-term seropositive donor. Highest concentrations of CMV DNA in both whole blood and plasma, however, were found in newly seropositive donors.

CONCLUSION

Prevalences of window period donations among seronegative donors and reactivations among long-term seropositive donors, as well as the CMV DNA concentration in whole blood and plasma samples from these donors, are comparable. Therefore, blood products from both groups could be used for patients at risk for TT-CMV, while those of newly seropositive donors seem to bear an increased risk.

Alternative blood products and clinical needs in transfusion medicine

The primary focus of national blood programs is the provision of a safe and adequate blood supply. This goal is dependent on regular voluntary donations and a regulatory infrastructure that establishes and enforces standards for blood safety. Progress in ex vivo expansion of blood cells from cell sources including peripheral blood, cord blood, induced pluripotent stem cells, and human embryonic stem cell lines will likely make alternative transfusion products available for clinical use in the near future. Initially, alloimmunized patients and individuals with rare blood types are most likely to benefit from alternative products. However, in developed nations voluntary blood donations are projected to be inadequate in the future as blood usage by individuals 60 years and older increases. In developing nations economic and political challenges may impede progress in attaining self-sufficiency. Under these circumstances, ex vivo generated red cells may be needed to supplement the general blood supply.

Xenotropic murine leukemia virus-related virus does not pose a risk to blood recipient safety

BACKGROUND

When xenotropic murine leukemia virus-related virus (XMRV) was first reported in association with chronic fatigue syndrome, it was suggested that it might offer a risk to blood safety. Thus, the prevalence of the virus among blood donors and, if present, its transmissibility by transfusion need to be defined.

STUDY DESIGN AND METHODS

Two populations of routine blood donor samples (1435 and 13,399) were obtained for prevalence evaluations; samples from a linked donor-recipient repository were also evaluated. Samples were tested for the presence of antibodies to XMRV-related recombinant antigens and/or for XMRV RNA, using validated, high-throughput systems.

RESULTS

The presence of antibodies to XMRV could not be confirmed among a total of 17,249 blood donors or recipients (0%; 95% confidence interval [CI], 0%-0.017%); 1763 tested samples were nonreactive for XMRV RNA (0%; 95% CI, 0%-0.17%). Evidence of infection was absent from 109 recipients and 830 evaluable blood samples tested after transfusion of a total of 3741 blood components.

CONCLUSIONS

XMRV and related murine leukemia virus (MLV) markers are not present among a large population of blood donors and evidence of transfusion transmission could not be detected. Thus, these viruses do not currently pose a threat to blood recipient safety and further actions relating to XMRV and MLV are not justified.

Surveillance of transfusion-transmissible infections comparison of systems in five developed countries

Most industrialized countries maintain surveillance programs for monitoring transmissible infection in blood donations, revising approaches to methodology and risk assessment as new threats emerge. A comparison of programs in the United States, Canada, France, the UK, and Australia indicates that they have similar function, although the structure of blood programs vary as does the extent and nature of formal ties with public health. The emergence of HIV in the late 1970s and early 1980s was key in recognizing that surveillance systems specific to blood transfusion were essential. Hence, most industrialized countries monitor transfusion-transmissible infections in donors and evaluate the impact of new testing and of predonation screening strategies. Emerging infections since HIV have had different transmission pathways and challenged blood programs to draw upon resources for a rapid and effective response, with recognition that the original focus on sexual/drug-related risk of HIV and hepatitis was inadequate. The focus of surveillance programs on new and emerging pathogens fulfills a key role in risk assessment and policy formulation. The precise nature of such activities varies by country because of the structure of the blood programs and surveillance systems, the strategic focus of the blood programs, and the epidemiology of disease in each country.

Is the number of blood products transfused associated with lower survival in children with acute lymphoblastic leukemia?

BACKGROUND

Blood transfusion during acute lymphoblastic leukemia (ALL) of childhood is scarcely documented. Children with ALL are immunosuppressed by both the disease and its therapy. Transfusion may contribute to the course of ALL through its transfusion-related immunomodulation (TRIM) effect.

PROCEDURE

Blood transfusion history and response to therapy for 108 children <16 years of age at the time of ALL diagnosis was documented. Clinical files, electronic records, and blood bank registries were scrutinized. Overall survival (OS) and event-free survival (EFS) in relation to blood product type and number of transfusions was determined. Hazard ratios (HR) for death and relapse were estimated through uni- and multivariate Cox regression analysis.

RESULTS

One hundred eight ALL patients were included. Median age was 6 years (range: 0-15 years). Ninety-seven patients (89.8%) were transfused. Median number of transfused products was seven (range: 0-345). After multivariate analysis, transfusion of >5 packed red blood cells (PRBC) remained a significant predictor for death (P = 0.003) and relapse (P = 0.011). For platelets, maximal significance was observed when >30 platelet concentrates (PC) were transfused (P < 0.001). When both, PRBC and PC were considered, maximal significance for predicting death was observed with transfusion of >30 blood products (P < 0.001).

CONCLUSIONS

The number of blood products transfused to children with ALL appears to be significantly associated with lower survival rates. This may reflect both the severity of the disease and the TRIM effect, which may decrease immune surveillance capacity and the probability of leukemic clone eradication.

Transmission of cytomegalovirus (CMV) infection by leukoreduced blood products not tested for CMV antibodies: a single-center prospective study in high-risk patients undergoing allogeneic hematopoietic stem cell transplantation (CME)

BACKGROUND

Measures to prevent transfusion-transmitted cytomegalovirus (TT-CMV) infection after hematopoietic stem cell transplantation (HSCT) include transfusion of CMV antibody-negative blood units and/or transfusion of leukoreduced cellular blood products. We assessed the incidence of TT-CMV in CMV-seronegative patients receiving CMV-seronegative HSC transplants, who were transfused with leukoreduced cellular blood products not tested for anti-CMV.

STUDY DESIGN AND METHODS

In a prospective observational study between 1999 and 2009, all HSCT patients received leukoreduced cellular blood products not tested for anti-CMV. Patients were screened for CMV serostatus and CMV-negative recipients of CMV-negative transplants were systematically monitored for TT-CMV clinically and by CMV nucleic acid testing. Anti-CMV antibodies (immunoglobulin [Ig]G and IgM) were assessed after three time intervals (Interval 1, study inclusion to Day +30 after HSCT; Interval 2, Day +30-Day +100; Interval 3, after Day +100).

RESULTS

Among 142 patients treated with allogeneic HSCT, 23 CMV-negative donor-patient pairs were identified. These 23 patients received 1847 blood products from 3180 donors. All patients remained negative for CMV DNA and none developed CMV-associated clinical complications. This results in a risk for TT-CMV per donor exposure of 0% (95% confidence interval, 0.0%-0.12%). However, 17 of 23 patients seroconverted for anti-CMV IgG, but none for anti-CMV IgM. CMV IgG seroconverters received significantly more transfusions per week than nonconverters.

CONCLUSION

The risk of TT-CMV is low in high-risk CMV(neg/neg) HSCT patients transfused with leukoreduced blood products not tested for anti-CMV. The cause of anti-CMV IgG seroconversion is most likely passive antibody transmission by blood products.

Seroprevalence and serum profile of cytomegalovirus infection among patients with hematologic disorders in Bahia State, Brazil

Human cytomegalovirus (CMV) is a ubiquitous herpesvirus with from 30% to 100% of the general population exhibiting prior exposure by serology. This cross-sectional study evaluated the serological profile of anti-CMV antibodies and two acute-phase reaction proteins in Haematologic Disorder Patients (HDPs) from Bahia State, Brazil. Immuno-chemiluminescence assays were performed to detect anti-CMV IgM and IgG antibodies. Serological levels of High Sensitivity C-Reactive Protein (CRPH) and Alpha-1-Acid Glycoprotein (AAG) were measured using immunonephelometry. A total of 470 HDPs were enrolled, 238 (50.6%) males and 232 (49.4%) females. The overall seroprevalence of CMV was 89.4%, directly proportional to age and to the amount of blood units transfused. There was no difference between seroprevalence rates according to gender (P = 0.12). Four HDPs (0.9%) were seropositives for anti-CMV IgM, only one could be characterized as recent acute infection. The most CMV seropositive HDPs had anti-CMV IgG in low titers. There was a tendency for females to have higher anti-CMV IgG titers than men (P < 0.05). CRPH levels were different among HDPs CMV negative and positive groups (P < 0.001). There was no difference in the AAG levels between groups (P = 0.15). The high CMV seroprevalence found underscores the importance of using strategies to provide "CMV safe" blood to HDPs who are at high risk of developing severe CMV infection. CRPH can be used as a biomarker associated with CMV seropositivity; however, more efforts are needed to better characterize the clinical profile of active CMV infection in this group of patients.