Donor risk factors for white blood cell antibodies associated with transfusion-associated acute lung injury: REDS-II leukocyte antibody prevalence study (LAPS)

The Dead Sea needs salt water… massively bleeding patients need whole blood: The evolution of blood product resuscitation

Whole blood, that is blood that is not manufactured into its component red blood cells (RBC) plasma, and platelets (PLT) units, was the mainstay of transfusion for many years until it was discovered that the component parts of a blood donation could be stored under different conditions thereby optimizing the storage length of each product. The use of low anti-A and -B titer group O whole blood (LTOWB) has recently been rediscovered for use in massively bleeding trauma patients. Whole blood has several advantages over conventional component therapy for these patients, including simplifying the logistics of the resuscitation, being more concentrated than whole blood that is reconstituted from conventional components, and providing cold-stored PLTs, amongst other benefits. While randomized controlled trials to determine the efficacy of using LTOWB in the resuscitation of massively bleeding trauma patients are currently underway, retrospective data has shown that massively bleeding recipients of LTOWB with traumatic injury do not have worse outcomes compared to patients who received conventional components and, in some cases, recipients of LTOWB have more favourable outcomes. This paper will describe some of the advantages of using LTOWB and will discuss the emerging evidence for its use in massively bleeding patients.

Male-predominant plasma transfusion strategy for preventing transfusion-related acute lung injury: a systematic review

OBJECTIVES

To assess 1) the effectiveness of male-predominant plasma transfusion strategy for preventing transfusion-related acute lung injury and related mortality; and 2) whether this effect varies across different patient subgroups.

DESIGN

Systematic Review and meta-analysis: Data were identified by querying MEDLINE and EMBASE (including proceedings of major conferences on blood transfusions), searching the Internet for hemovigilance reports, reviewing reference lists of eligible articles and contacting experts in the field. Eligible were all studies reporting transfusion-related acute lung injury incidence, all-cause mortality (primary outcomes), hospital length of stay, time to extubation, PaO2/FIO2-ratio or blood pressure changes (secondary outcomes) in recipients of plasma transfusions containing relatively more plasma from individuals at low risk of carrying leukocyte-antibodies ("male plasma") than those receiving comparator plasma ("control plasma"). No limits were placed on study design, population or language. The only exclusion criteria were non-human subjects and lack of control group. Prespecified study quality indicators (including risk of bias assessment) and potential effect modifiers were tested using Cochran's Q Test. Final analyses using random-effects models and I2 to assess heterogeneity were performed in the subset of studies judged to provide the best evidence and separately for significantly different subgroups using STATA 12.1 (StataCorp, College Station, TX).

SETTING

As per primary studies.

PATIENTS/SUBJECTS

As per primary studies.

INTERVENTIONS

As per primary studies (generally: exposure to plasma containing relatively more male plasma than comparator plasma).

MEASUREMENTS AND MAIN RESULTS

From a total of 850 retrieved records, we identified 45 eligible studies. For transfusion-related acute lung injury incidence, final analysis was restricted to 13 cohort studies and one randomized controlled trial in which transfusion-related acute lung injury cases only involved plasma transfusions. Risk of transfusion-related acute lung injury and mortality in plasma recipients exposed to men when compared with control plasma were 0.27 (95% CI, 0.20-0.38; p < 0.001; I = 0%; n = 14; 286 events) and 0.89 (95% CI, 0.80-1.00; p = 0.04; I = 79%; n = 7; 5, 710 events), respectively. No other significant interactions were found. Secondary outcomes showed similar results but were less reported and the studies were more heterogeneous. Sensitivity analyses did not alter the results. There was no evidence of publication bias.

DISCUSSION

More than 800 million people in 17 countries are subject to male-predominant plasma transfusion policy and at least three more countries are planning or considering adoption of this strategy. On the basis of most observational data, judged to be of high quality, male-predominant plasma transfusion strategy reduces plasma-related transfusion-related acute lung injury incidence and possibly mortality. There was no evidence that the effect differs across patient subgroups, but power to detect such differences was low.

Lot-to-lot variability in HLA antibody screening using a multiplexed bead-based assay

BACKGROUND

Identifying antibodies to HLA (anti-HLA) by solid-phase assays is used to screen blood donors to mitigate transfusion-related acute lung injury risk. Various cutoffs for detection assays have been proposed in the literature; however, these do not take into consideration lot-to-lot variability of commercially available assays.

STUDY DESIGN AND METHODS

Samples from 93 nontransfused males were tested using five different lots of a multiplex bead-based anti-HLA detection kit. A subset of 17 samples was tested on 5 days using a single lot. An additional 96 samples from donations with varied anti-HLA levels were tested using kits from two different lots. Results were reported as a normalized background (NBG) ratio.

RESULTS

For the 93 nontransfused donors, NBG values generated using the reference lot were significantly higher than those obtained with three of the four comparator lots. However, for the 96 samples with low-, moderate-, and higher-level anti-HLA, Class I (CL-I) values were 1.4 times lower and Class II (CL-II) values were 1.2 times lower using the reference versus comparator lot. For CL-I antibodies the between-lot standard deviation (SD) was 1.36 (95% confidence interval [CI], 1.19-1.60), while the between-day SD was 1.27 (95% CI, 1.08-1.52). Similarly, for CL-II antibodies the between-lot SD was 0.81 (95% CI, 0.70-0.95), while the between-day SD was 0.50 (95% CI, 0.43-0.60).

CONCLUSIONS

There is interlot variability in the tested HLA detection assay as well as significant bias between lots. It may be reasonable to develop a new cutoff when a new lot is obtained.

The National Heart, Lung, and Blood Institute retrovirus epidemiology donor studies (Retrovirus Epidemiology Donor Study and Retrovirus Epidemiology Donor Study-II): twenty years of research to advance blood product safety and availability

The Retrovirus Epidemiology Donor Study (REDS), conducted from 1989 to 2001, and the REDS-II, conducted from 2004 to 2012, were National Heart, Lung, and Blood Institute-funded, multicenter programs focused on improving blood safety and availability in the United States. The REDS-II also included international study sites in Brazil and China. The 3 major research domains of REDS/REDS-II have been infectious disease risk evaluation, blood donation availability, and blood donor characterization. Both programs have made significant contributions to transfusion medicine research methodology by the use of mathematical modeling, large-scale donor surveys, innovative methods of repository sample storage, and establishing an infrastructure that responded to potential emerging blood safety threats such as xenotropic murine leukemia virus-related virus. Blood safety studies have included protocols evaluating epidemiologic and/or laboratory aspects of human immunodeficiency virus, human T-lymphotropic virus 1/2, hepatitis C virus, hepatitis B virus, West Nile virus, cytomegalovirus, human herpesvirus 8, parvovirus B19, malaria, Creutzfeldt-Jakob disease, influenza, and Trypanosoma cruzi infections. Other analyses have characterized blood donor demographics, motivations to donate, factors influencing donor return, behavioral risk factors, donors' perception of the blood donation screening process, and aspects of donor deferral. In REDS-II, 2 large-scale blood donor protocols examined iron deficiency in donors and the prevalence of leukocyte antibodies. This review describes the major study results from over 150 peer-reviewed articles published by these 2 REDS programs. In 2011, a new 7-year program, the Recipient Epidemiology and Donor Evaluation Study-III, was launched. The Recipient Epidemiology and Donor Evaluation Study-III expands beyond donor-based research to include studies of blood transfusion recipients in the hospital setting and adds a third country, South Africa, to the international program.

Biospecimen repositories: are blood donors willing to participate?

BACKGROUND

Sponsored by the National Heart, Lung, and Blood Institute, the Retrovirus Epidemiology Donor Studies (REDS-I/-II) have conducted epidemiologic, laboratory, and survey research on volunteer blood donors. Some studies request additional permission to store biospecimens for future studies. The representativeness and applicability of studies performed using repositories may be reduced by low participation rates.

STUDY DESIGN AND METHODS

Demographics from subjects consenting to participate in the 2007 REDS-II Leukocyte Antibodies Prevalence Study (LAPS) repository were compared to "study-only" subjects. Data from the 1998 REDS-I survey of donor opinion regarding storage and use of biospecimens were also explored.

RESULTS

Overall, 91% of LAPS subjects agreed to participate in the repository. Odds of repository participation were lower among African American and Hispanic donors, 35- to 44-year-olds, donors who had not completed high school, and donors from one geographic location, regardless of other variables. Survey data from 1998 revealed that 97% of respondents approved of long-term storage of biospecimens, although only 87% indicated that they would personally participate. Many respondents would require notification or their permission be obtained before participation. Minority respondents would require permission or notification more often and were less certain they would personally participate in a repository.

CONCLUSION

Blood donors are quite willing to participate in biospecimen repositories. Regional differences and lower odds of participation in the minority blood donor population may result in a reduced number of biospecimens available for study and a decreased ability to definitely answer specific research questions in these populations.

The role of neutrophils in the pathogenesis of transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is the major cause of transfusion related morbidity and mortality, world wide. Efforts to reduce or eliminate this serious complication of blood transfusion are hampered by an incomplete understanding of its pathogenesis. Currently, TRALI is thought to be mediated by donor alloantibodies directed against host leukocytes or the result of 2 distinct clinical events. For both proposed mechanisms, the neutrophil is the key effector cell. This article reviews TRALI pathophysiology, explores the role of the neutrophil, details practical information for appropriate diagnosis and promotes further studies into the pathogenesis of TRALI.

The effect of previous pregnancy and transfusion on HLA alloimmunization in blood donors: implications for a transfusion-related acute lung injury risk reduction strategy

BACKGROUND

Antibodies to human leukocyte antigens (HLA) in donated blood have been implicated as a cause of transfusion-related acute lung injury (TRALI). A potential measure to reduce the risk of TRALI includes screening plateletpheresis donors for HLA antibodies. The prevalence of HLA antibodies and their relationship to previous transfusion or pregnancy in blood donors was determined.

STUDY DESIGN AND METHODS

A total of 8171 volunteer blood donors were prospectively recruited by six US blood centers from December 2006 to May 2007. Donors provided a detailed history of pregnancy and transfusion and a sample for HLA Class I and II antibody testing by multiantigen bead flow analysis.

RESULTS

A total of 8171 donors were enrolled; 7920 (96.9%) had valid HLA antibody test results and 7841 (99%) of those had complete pregnancy and transfusion information. The prevalence of any HLA antibody was similar in nontransfused (n = 1138) and transfused (n = 895) men, 1.0% versus 1.7% (p = 0.16). HLA antibodies were detected in 17.3% of all female donors (n = 5834) and in 24.4% of those with a history of previous pregnancy (n = 3992). The prevalence of HLA antibodies increased in women with greater numbers of pregnancy: 1.7% (zero), 11.2% (one), 22.5% (two), 27.5% (three), and 32.2% (four or more pregnancies; p < 0.0001).

CONCLUSION

HLA Class I and Class II antibodies are detectable at low prevalence in male donors regardless of transfusion and in female donors without known immunizing events. The prevalence of HLA antibodies increases significantly with more pregnancies. These data will allow blood centers to estimate the impact of HLA antibody testing as a potential TRALI risk reduction measure.

Transfusion-related acute lung injury: current concepts for the clinician

The leading cause of transfusion-related morbidity and mortality in the United States is transfusion-related acute lung injury (TRALI). Diagnostic criteria for TRALI have recently been developed and primarily consist of hypoxia and bilateral pulmonary edema occurring during or within 6 h of a transfusion in the absence of cardiac failure or intravascular volume overload. The primary differential diagnosis is transfusion-associated circulatory overload and differentiation can be difficult. Treatment is supportive with oxygen and mechanical ventilation. Diuresis is not indicated and the role of steroids is unproven. Patients typically recover within a few days. All types of blood products have been associated with TRALI, however, the plasma-rich components, such as fresh frozen plasma and apheresis platelets, have been most frequently implicated. The pathogenesis of TRALI is not completely understood. Leukocyte antibodies in donor plasma have been implicated in most cases with antibodies directed at human leukocyte antigen (HLA) class I, HLA class II or neutrophil-specific antigens, particularly HNA-3a. Activation of pulmonary endothelium is important in the development of TRALI and may account for most cases being observed in surgical or intensive care unit patients. Transfused leukoagglutinating antibodies bind to recipients' neutrophils localized to pulmonary endothelium resulting in activation and release of oxidases and other damaging biologic response modifiers that cause capillary leak. In a minority of TRALI cases, no antibodies are identified and it is postulated that neutrophil priming factors in the transfused component can mediate TRALI in a patient with pulmonary endothelial activation, the so called "two hit" mechanism. Recognition of the role of anti-leukocyte antibodies has led to new strategies to reduce the risk of TRALI. Female blood donors with a previous pregnancy frequently have HLA antibodies with an overall prevalence of 24% and increasing prevalence related to the number of previous pregnancies. Since HLA antibodies have been implicated in TRALI, blood centers have adopted policies to produce plasma components primarily from male donors. Strategies to reduce the risk from apheresis platelets are problematic and are likely to involve testing female apheresis platelet donors for HLA antibodies. Much more research is needed to understand the blood component and patient risk factors for TRALI so that novel strategies for treatment and additional measures to reduce the risk of TRALI can be developed.

Long-term in vitro reactivity for human leukocyte antigen antibodies and comparison of detection using serum versus plasma

BACKGROUND

Human leukocyte antigen (HLA) antibodies are a possible cause of transfusion-related acute lung injury (TRALI), and fluorescent bead assays are often used for antibody detection. Serum is the manufacturer's recommended sample, but plasma may be easier to obtain for studies of HLA antibody prevalence and TRALI case investigations.

STUDY DESIGN AND METHODS

Specimens were obtained from 44 multiparous females positive for the presence of HLA antibodies by lymphocytotoxicity testing at least 13 years prior and from 1000 contemporary blood donors. Screening tests were performed using a multiplex bead-based assay. In addition to comparing results obtained with paired plasma and serum samples, the effects of storage at 4 degrees C for 1 week and of multiple freeze-thaw cycles were evaluated.

RESULTS

Of 42 evaluable subjects with HLA antibodies documented more than 13 years earlier, only 1 showed loss of detectable antibodies, with 39 (93%) positive in the screening assay for HLA Class I and 24 (57%) positive in the screening assay for HLA Class II antibodies. In 968 evaluable contemporary donors, 291 screened positive for the presence of HLA Class I and 206 for HLA Class II antibodies using a low assay cutoff. Screening test concordance using paired plasma and serum samples was high, particularly for subjects with higher-level antibodies. Refrigeration of samples for 1 week did not significantly affect assay results, while repeated freeze-thaw cycles caused a decrement in signal level.

CONCLUSION

Serum and plasma samples gave concordant results in the majority of cases, particularly for specimens with higher-level antibodies. High-level HLA antibodies were present in most individuals for more than 13 years.