Absence of blood donors' anti-SARS-CoV-2 antibodies in pre-storage leukoreduced red blood cell units indicates no role of passive immunity for blood recipients

Transfer of vaccine antibodies (Ab) from donors to recipients after transfusion of packed red blood cells (RBC) is supposed, thus affecting the recipients' response to vaccinations. In this prospective study, SARS-CoV-2 IgG level in donors' serum and RBC supernatant samples was assessed. Among 346 subjects, 280 were referred for hyperimmune plasma donation and 30 for whole blood donations. All units underwent pre-storage filtration, and residual plasma volume was 18±18 mL. The mean total IgG and IgM levels were 171.43 ± 48.79 and 11.43 ± 10.69 mg/dL respectively, with significant reduction after plasma depletion and filtration (IgG 5.86 ± 5.2 and IgM 1.43 ± 3.78, p < 0.05). Anti-COVID-19 Ab were identified in serum of 28/30 (93.5%) blood donors but were absent in all blood units. The mean value of anti-SARS-CoV-2 IgG level in donors' serum samples and in RBC units was 8.80 S/C (range 0.01-23.4) and 0.11 (range 0.01-0.37) S/C, respectively (p<0.05). This study shows deplasmation and leukodepletion of RBC units ensured removal of IgG content and no red blood cell unit was reactive for anti-COVID-19 antibodies even from donors with high serum titre. These findings demonstrate that deplasmated and leukodepleted RBCs are not to be considered blood products containing substantial amounts of immune globulin, and differently from other blood derived-products containing Ab, transfusions with deplasmated and leukodepleted RBCs do not require delayed vaccinations and a revision of current recommendations is requested.

The Role of Complement in Transfusion-Related Acute Lung Injury

Transfusion-related acute lung injury (TRALI) is a life-threatening complication of acute respiratory distress occurring within 6 hours of blood transfusion. TRALI is one of the leading causes of transfusion-related fatalities and specific therapies are unavailable. Neutrophils are recognized as the major pathogenic cells, whereas T regulatory cells and dendritic cells appear to be important for protection against TRALI. The pathogenesis, however, is complex and incompletely understood. It is frequently postulated that the complement system plays an important role in the TRALI pathogenesis. In this article, we assess the evidence regarding the involvement of complement in TRALI from both human and animal studies. We hypothesize about the potential connection between the complement system and neutrophils in TRALI. Additionally, we draw parallels between TRALI and other acute pulmonary disorders of acute lung injury and acute respiratory distress syndrome regarding the involvement of complement. We conclude that, even though a role for complement in the TRALI pathogenesis seems plausible, studies investigating the role of complement in TRALI are remarkably limited in number and also present conflicting findings. Different types of TRALI animal models, diverse experimental conditions, and the composition of the gastrointestinal microbiota may perhaps all be factors which contribute to these discrepancies. More systematic studies are warranted to shed light on the contribution of the complement cascade in TRALI. The underlying clinical condition of the patient, which influences the susceptibility to TRALI, as well as the transfusion factor (antibody-mediated vs non–antibody-mediated), will be important to take into consideration when researching the contribution of complement. This should significantly increase our understanding of the role of complement in TRALI and may potentially result in promising new treatment strategies.

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Studies investigating complement and TRALI are limited in number and present conflicting findings.

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Systematic investigation is needed to better understand the contribution of the complement cascade in TRALI.

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Future studies in this area should consider both the clinical susceptibility of the patient as well as the effect of transfusion factors.

Risk factors, management and prevention of transfusion-related acute lung injury: a comprehensive update

Introduction: Despite mitigation strategies that include the exclusion of females from plasma donation or the exclusion of females with a history of pregnancy or known anti-leukocyte antibody, transfusion-related acute lung injury (TRALI) remains a leading cause of transfusion-related morbidity and mortality. Areas covered: The definition of TRALI is discussed and re-aligned with the new Berlin Diagnostic Criteria for the acute respiratory distress syndrome (ARDS). The risk factors associated with TRALI are summarized as are the mitigation strategies to further reduce TRALI. The emerging basic research studies that may translate to clinical therapeutics for the prevention or treatment of TRALI are discussed. Expert opinion: At risk patients, including the genetic factors that may predispose patients to TRALI are summarized and discussed. The re-definition of TRALI employing the Berlin Criteria for ARDS will allow for increased recognition and improved research into pathophysiology and mitigation to reduce this fatal complication of hemotherapy.

Evaluation of a new microbeads assay for granulocyte antibody detection

BACKGROUND

To reduce the risk of transfusion-associated acute lung injury (TRALI), a high number of plasma donors were tested for human leukocyte antigen (HLA) and human neutrophil antigen (HNA) antibodies. For HNA antibody detection, the gold standard is a combination of the granulocyte immunofluorescence test (GIFT) and the granulocyte agglutination test (GAT). However, these tests are not suitable for a high-throughput of samples.

STUDY DESIGN AND METHODS

To evaluate the new generation of the LABScreen MULTI assay (One Lambda, Inc.), which has special new beads for all the known HNA specificities, including HNA-3a, 97 sera samples containing well-defined HNA antibodies were used. For background testing, we used 91 samples from plasma donors previously identified by GAT, GIFT, and the monoclonal antibody-specific immobilization of granulocyte antigens (MAIGA) assay.

RESULTS

Compared with previous tests, the new LABScreen MULTI assay was highly specific for the HNA-1a, HNA-1b, HNA-2, and HNA-3a antibody specificities required to prevent TRALI. Ninety-eight percent of the HNA-1a, HNA-1b, and HNA-2 antibodies could be detected as true positive; and 90% of the HNA-3a antibodies were recognized correctly as positive. False-positive reactions were identified in 5.5% of samples that previously tested negative.

CONCLUSION

The detection of HNA-3a antibody specificities could be integrated into the new LABScreen MULTI assay; however, we detected only 90%. In addition, we detected further HNA antibodies, such as HNA-1c, HNA-1d, and some HNA-3b and HNA-4a antibodies. The new generation of LABScreen MULTI is a great step toward feasible high-throughput testing for HNA antibodies. Nevertheless, GIFT and GAT remain the gold-standard methods for the differentiation of rare and currently unknown HNA specificities.

FCGR3B gene frequencies among ethnic Thai blood donors from a regional hospital in Eastern Thailand

The FCGR3B gene encodes three human neutrophil antigens which consist of HNA-1a, HNA-1b, and HNA-1c. These antigens are encoded by three alleles in the FCGR3B locus: FCGR3B*01, FCGR3B*02, and FCGR3B*03 alleles, respectively. The frequencies of FCGR3B alleles have been reported in different ethnic populations. This study compared the FCGR3B gene frequencies among 230 unrelated healthy Eastern Thai blood donors in Rayong hospital with the previously published studies. The polymerase chain reaction-sequence-specific primers method was performed to determine FCGR3B genotypes. The results showed that the allele frequencies of FCGR3B*01, FCGR3B*02, and FCGR3B*03 were 0.722, 0.274, and 0.009, respectively. The FCGR3B*01 and FCGR3B*02 frequencies found in the Eastern Thais were similar to the previous reports investigating in Northern Thais, Chinese Han, Taiwanese, and Japanese populations. Interestingly, our data showed statistically significant difference (P < 0.05) to Central Thais, Korean, Indian, Turkish, Australian, Tunisian, American, German, and Italian populations. In addition, one FCGR3Bnull , which represents a gene deletion, was also found in this study. This information is important not only for the assessment of neutrophil antibody-mediated clinical conditions and for disease association studies but also for anthropological studies.

The effect of C1-inhibitor in a murine model of transfusion-related acute lung injury

BACKGROUND AND OBJECTIVE

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-related morbidity and mortality. Specific therapy is lacking. We assessed whether C1-inhibitor attenuates lung injury in a 'two-hit' TRALI model.

METHODS

Mice were primed with lipopolysaccharide, subsequently TRALI was induced by MHC-I antibodies. In the intervention group, C1-inhibitor was infused concomitantly. Mice were supported with mechanical ventilation. After 2 h, mice were killed, lungs were removed and bronchoalveolar lavage fluid (BALF) was obtained.

RESULTS

Injection of MHC-I antibodies induced TRALI, illustrated by an increase in wet-to-dry ratio of the lungs, in BALF protein levels and in lung injury scores. TRALI was further characterized by complement activation, demonstrated by increased BALF levels of C3a and C5a. Administration of C1-inhibitor resulted in increased pulmonary C1-inhibitor levels with high activity. C1-inhibitor reduced pulmonary levels of complement C3a associated with improved lung injury scores. However, levels of pro-inflammatory mediators were unaffected.

CONCLUSION

In a murine model of TRALI, C1-inhibitor attenuated pulmonary levels of C3a associated with improved lung injury scores, but with persistent high levels of inflammatory cytokines.

Ninety-six suspected transfusion related acute lung injury cases: Investigation findings and clinical outcome

Transfusion related acute lung injury (TRALI) is one of the complications of blood transfusion and can result in major morbidity or mortality. The diagnosis depends upon the application of strict clinical criteria defining acute lung injury (ALI) and a temporal relationship to blood transfusion. We present the clinical and immunogenetic findings of 96 suspected TRALI cases investigated between 1996 and 2004. During this time period the national haemovigilance scheme (UK) defined TRALI as a reaction occurring either during or within 24 h of blood transfusion. Using clinical, laboratory and post mortem evidence, 64/96 cases could be defined as TRALI in our series. Sensitive techniques were employed to screen for HLA class I, class II and granulocyte specific antibodies in donor serum. Donor derived antibodies were detected in 58/64 (90%) of cases. Recipient derived DNA or cells were not always available but incompatibility was confirmed by the presence of the cognate antigen on recipient leucocytes or by crossmatching in 47/64 (73%) of cases. Cases referred prior to 2001 were not tested for HLA class II antibodies. By applying strict clinical criteria and using sensitive techniques a white blood cell antibody mediated immunological pathophysiology can be implicated in the majority TRALI cases.

External quality assessment of human neutrophil antigen (HNA)-specific antibody detection and HNA genotyping from 2000 to 2012

Since 2000, Quality Assurance (QA) exercises for the detection and identification of granulocyte antibodies and DNA typing for human neutrophil antigens (HNA) have been distributed within the International Granulocyte Immunobiology Workshops, which are linked to International Society of Blood Transfusion. The exercises were standardised at the outset to enable laboratory performance to be monitored. Between 2000 and 2012, nine exercises were distributed to 20 laboratories. Overall, 45 examples of 42 unique samples containing defined granulocyte reactive antibodies were distributed for serological analysis together with 20 samples for HNA genotyping. The level of satisfactory serological performance was initially set at 50% and later increased to 70%, while the 'cut-off' for HNA genotyping was set at 100% after 2008. Failure to achieve the minimum score in the QA exercises in consecutive years resulted in temporary exclusion. In 2000, the 15 participating laboratories had a mean score of 56.1% for serological analysis and 13 laboratories attempted HNA-1a and -1b genotyping, while 11 attempted HNA-1c typing. Steady improvements in proficiency for serological testing and HNA typing occurred in subsequent exercises. In 2012, the mean score for serology was 88.5% and 12/13 laboratories scored 100% for HNA-1a, -1b, -1c, -3a, -3b, -4a, -4bw, -5a and -5bw genotyping. These QA exercises have provided an invaluable tool to monitor and improve the standard of granulocyte immunology investigations for participating laboratories, thereby enhancing performance for both clinical investigations and donor screening programmes to reduce the incidence of TRALI.

The frequencies of human neutrophil alloantigens in the Chinese Han population of Guangzhou

BACKGROUND

Antibodies against polymorphic structures on human neutrophil antigens (HNAs) play a role in alloimmune-mediated neutropenia and are the leading cause of antibody-mediated transfusion-related acute lung injury (TRALI). This study aimed to determine the frequencies of HNAs in the major Han ethnic group living in Guangdong Province, Southern China.

STUDY DESIGN AND METHODS

A total of 493 healthy Chinese Han blood donors from Guangzhou were recruited. DNA samples were isolated and typed for all five HNA-1, -2, -3, -4, and -5 systems using allele-specific polymerase chain reaction approaches. Results were compared with available data from other Chinese cohorts and other Asian and Caucasian populations.

RESULTS

In this cohort, the gene frequency for HNA-1a (0.667) was approximately twice that of HNA-1b (0.333). In contrast to Caucasian populations, HNA-1a represents the most frequent allele in the Chinese population. HNA-3 system genotyping revealed comparable frequencies for HNA-3a (0.738) and -3b (0.262) in Chinese and Caucasian populations. Homozygous HNA-3 bb individuals were found in 5.64% of our cohort. HNA-4 genotyping revealed no HNA-4 bb homozygous individuals. In contrast, HNA-5 bb homozygous individuals represented 2.43% of the population. Typing the HNA-2 system for the single-nucleotide polymorphism C42G showed that the C-allele (69%) is overrepresented and is associated with an increased number of HNA-2a-positive neutrophil subpopulations.

CONCLUSION

This study describes for the first time the frequencies of all HNA systems, including the newly identified HNA-3, within one cohort of Chinese Han population. Comparison with Caucasian populations may allow assessment of anti-HNA alloimmunization and estimation of alloimmune neutropenia and TRALI incidence in Chinese populations.

[Transfusion-related acute lung injury]

The term Transfusion-Related Acute Lung Injury (TRALI) was coined in 1985. It is a relatively rare, life-threatening clinical syndrome characterized by acute respiratory failure and non-cardiogenic pulmonary edema during or following a blood transfusion. Although its true incidence is unknown, a rate 1 out of every 5000 transfusions has been quoted. TRALI has been the most common cause of transfusion-related fatalities during three years in the USA. Two different etiologies have been proposed. The first is a single antibody-mediated event involving the transfusion of anti-HLA or antigranulocyte antibodies into patients whose leukocytes express the cognate antigens. The second is a two-event model: the first event is related to the clinical condition of the patient (sepsis, trauma, etc.) resulting in pulmonary endothelial activation and neutrophil sequestration, and the second event is the transfusion of a biologic response modifier that activates these adherent polymorphonuclear leukocytes resulting in endothelial damage and capillary leak. The patient management is support as needed based on the severity of the clinical picture and strategies to prevent TRALI are focused on: donor-exclusion policies, product management strategies and avoidance of unnecessary transfusions.

Transfusion-Related Acute Lung Injury — A Review

Transfusion-related acute lung injury (TRALI), a type of non-cardiogenic pulmonary oedema related to blood transfusion, is gaining prominence as a common adverse event related to blood transfusions in hospitals. Various mechanisms have been postulated to cause TRALI including both antibody-related and non-immune mechanisms. Although transfusion of all types of blood components have been implicated, by far the commonest product related to TRALI was, until recently, fresh frozen plasma, especially that obtained from female donors. However the use of male-only plasma donation in the UK has resulted in an increased observance of TRALI with platelet and red cell transfusions. The diagnosis of this condition is primarily one of exclusion of other causes of pulmonary oedema, with specialist laboratory tests performed to support the diagnosis. The management of TRALI is early diagnosis and good supportive care with, occasionally, ventilatory support. An increased awareness of this complication among intensive care physicians is desirable to prevent one of the commonest and most frequently under-recognised transfusion-related adverse events of the present day.

Transfusion-related acute lung injury following intravenous anti-D administration in an adolescent

Transfusion-related acute lung injury (TRALI) is associated with administration of all plasma containing blood products. We present a 14-year-old adolescent diagnosed with idiopathic thrombocytopenic purpura who developed acute respiratory insufficiency compatible with TRALI within 5 hr following intravenous anti-D. Full blown noncardiogenic pulmonary edema was noted after 9 hr. Mechanical ventilation was not required and the patient made a full recovery after 36 hr. Analysis of the anti-D preparation revealed reactivity against the neutrophil FcgammaRIIIb. A postinfusion serum sample contained antibodies against class I human HLA-A11 antigen. Clinicians should consider TRALI in patients developing unexplained dyspnea after receiving intravenous anti-D.

Transfusion-Related Acute Lung Injury (TRALI): Current Clinical and Pathophysiologic Considerations

Transfusion-related acute lung injury (TRALI) is a rare transfusion reaction presenting as respiratory distress during or after transfusion of blood products. TRALI varies in severity, and mortality is not uncommon. TRALI reactions have equal gender distributions and can occur in all age groups. All blood products, except albumin, have been implicated in TRALI reactions. TRALI presents as acute respiratory compromise occurring in temporal proximity to a transfusion of a blood product. Other causes of acute lung injury should be excluded in order to definitively diagnose TRALI. Clinically and pathologically, TRALI mimics acute respiratory distress syndrome (ARDS), with neutrophil-derived inflammatory chemokines and cytokines believed to be involved in the pathogenesis of both entities. Anti-HLA and anti-neutrophil antibodies have been implicated in some cases of TRALI. Treatment for TRALI is supportive; prevention is important. It is suspected that TRALI is both underdiagnosed and underreported. One of the difficulties in the evaluation of potential TRALI reactions is, until recently, the lack of diagnostic criteria. A group of transfusion medicine experts, the American-European Consensus Conference (AECC), recently met and developed diagnostic criteria of TRALI, as well as recommendations for management of donors to prevent future TRALI reactions. In light of the AECC consensus recommendations, we report an incident of TRALI in an oncology patient as an example of the potential severity of the lung disease and the clinical and laboratory evaluation of the patient. We also review the literature on this important complication of blood transfusion that internists may encounter.

Mechanisms of transfusion-related acute lung injury (TRALI): anti-leukocyte antibodies

There is abundant evidence that leukocyte antibodies in blood donor products are somehow involved in transfusion-related acute lung injury (TRALI). Human leukocyte antigen (HLA) class I, HLA class II, and neutrophil-specific antibodies in the plasma of both blood donors and recipients have been implicated in the pathogenesis of TRALI. The case for a relationship between leukocyte antibodies and TRALI is more compelling if concordance between the antigen specificity of the leukocyte antibodies in the donor plasma and the corresponding antigen on the cells of the affected recipient is demonstrated. Such antibody-antigen concordance can be investigated by typing the recipient for the cognate leukocyte antigens or by cross-matching the donor plasma against the recipient's leukocytes. Two proposed pathophysiologic mechanisms for TRALI have received the most attention: the antibody hypothesis and the two-event hypothesis. The final common pathway in all of the proposed pathogenic mechanisms of TRALI is increased pulmonary capillary permeability, which results in movement of plasma into the alveolar space causing pulmonary edema. A typical TRALI serologic workup consists of tests for HLA class I and II and neutrophil-specific antibodies. The use of flow cytometry and HLA-coated microbeads is recommended for detection of HLA antibodies in plasma of implicated blood donors and a combination of the granulocyte agglutination test and granulocyte immunofluorescence test for detection of neutrophil-specific antibodies. Genotyping for class I and II HLA and for a limited number of neutrophil antigens may also be helpful in establishing antibody-antigen concordance.

Transfusion-related acute lung injury

PURPOSE OF REVIEW

Transfusion-related acute lung injury is an uncommon complication of blood transfusion typically manifested by shortness of breath, fever, and hypotension. Transfusion-related acute lung injury is an important cause of transfusion-related morbidity and mortality.

RECENT FINDINGS

Much about the pathogenesis, treatment, and prevention of transfusion-related acute lung injury is poorly understood or is controversial. There is increasing recognition that transfusion-related acute lung injury is an important clinical syndrome, causing most transfusion-related deaths.

SUMMARY

In this report, what is known about transfusion-related acute lung injury is summarized with particular emphasis on recent studies. Some of the areas in which knowledge and/or consensus are currently lacking are identified.

Transfusion-related acute lung injury (TRALI): a serious adverse event of blood transfusion

BACKGROUND AND OBJECTIVES

Analyses of fatal transfusion reactions in the UK and USA have shown that transfusion-related acute lung injury (TRALI) is among the most common causes of fatal transfusion reactions.

MATERIAL AND METHODS

Review of the literature was used to analyse TRALI.

RESULTS

TRALI is characterized by acute respiratory distress and non-cardiogenic lung oedema developing during, or within 6 h of, transfusion. In atypical cases, TRALI can become symptomatic much later. TRALI must be carefully differentiated from transfusion-associated circulatory overload. In its fulminant presentation, TRALI can be clinically indistinguishable from acute respiratory distress syndrome occurring as a result of other causes. The severity of TRALI depends upon the susceptibility of the patient to develop a more clinically significant reaction as a result of an underlying disease process, and upon the nature of triggers in the transfused blood components, including granulocyte-binding alloantibodies (immune TRALI) or neutrophil-priming substances such as biologically active lipids (non-immune TRALI). Immune TRALI, which occurs mainly after the transfusion of fresh-frozen plasma and platelet concentrates, is a rare event (about one incidence per 5000 transfusions) but frequently ( approximately 70%) requires mechanical ventilation (severe TRALI) and is not uncommonly fatal (6-9% of cases). Non-immune TRALI, which occurs mainly after the transfusion of stored platelet and erythrocyte concentrates, seems to be characterized by a more benign clinical course, with oxygen support sufficient as a form of therapy in most cases, and a lower mortality than immune TRALI.

CONCLUSIONS

By virtue of its morbidity and mortality, TRALI has become one of the most serious current complications of transfusion. To prevent further antibody-mediated cases, the evaluation of TRALI should include leucocyte antibody testing of implicated donors. However, further studies are necessary for the prevention of this serious transfusion complication.

A prospective randomized trial of a prophylactic platelet transfusion trigger of 10 x 109 per L versus 30 x 109 per L in allogeneic hematopoietic progenitor cell transplant recipients

BACKGROUND

The impact of lowering the platelet (PLT) count threshold for prophylactic PLT transfusion on bleeding and PLT use in allogeneic hematopoietic progenitor cell (HPC) transplant recipients is a matter of debate.

STUDY DESIGN AND METHODS

In 166 patients, randomly assigned to receive prophylactic PLT transfusion at a trigger level less than 10 x 10(9) PLTs per L (T10; n = 79) or less than 30 x 10(9) per L (T30; n = 87), the number of PLT and red blood cell (RBC) transfusions given and the number of hemorrhagic events (WHO Grades 2-4) were recorded.

RESULTS

No significant differences were found between the two groups regarding the clinical outcome variables (i.e., bacteremia, engraftment, graft-vs.-host disease [GVHD], hospital stay, death, and survival) or in the median total number of RBC transfusions given. The incidence, in Group T10 18 percent (14/79) and in Group T30 15 percent (13/87), as well as the type of bleeding were comparable. No deaths were attributed to hemorrhages. The number of PLT units transfused, however, was significantly lower in Group T10 (median, 4; range, 0-32), than in Group T30 (median, 10; range, 0-48; p < 0.001). Apart from the trigger level, the day of engraftment, the presence of acute GVHD, or bacteremia also affected the number of PLT transfusions.

CONCLUSION

A prophylactic PLT transfusion trigger level of less than 10 x 10(9) PLTs per L instead of less than 30 x 10(9) PLTs per L in allogeneic HPC transplant recipients was found to be safe and resulted in a decreased use of PLTs.

Syndrome de détresse respiratoire aiguë post-transfusionnel : une pathologie méconnue

Transfusion related acute lung injury (TRALI) is a rare but potentially severe complication of blood transfusion, manifested by pulmonary oedema, fever and hypotension. The signs and symptoms are often attributed to other clinical aspects of a patient's condition, and therefore, TRALI may go unrecognised. It has been estimated to be the third cause of transfusion related mortality, so it should be better diagnosed. Cases are related to multiple blood units, such as white blood cells, red blood cells, fresh frozen plasma, platelets or intravenous immunoglobulins. Physiopathology of TRALI is poorly understood, and still controversial. It is often due to an immunological conflict between transfused plasma antibodies and recipients' blood cells. These antibodies are either HLA (class I or II) or granulocyte-specific. They appear to act as mediators, which result in granulocytes aggregation, activation and micro vascular pulmonary injury. Lipids or cytokines in blood units are also involved as TRALI priming agents. Diagnosis is based on antibody screening in blood components and on specific-antigen detection in the recipient. The screening of anti-HLA or anti-granulocytes is recommended as part of prevention for female donors who had been pregnant. Preventative measures should also include leucoreduction and measures to decrease the amount of priming agents in blood components. In this article, we summarise what is known about TRALI, and we focus attention on unanswered questions and controversial issues related to TRALI.

Flow-cytometric approach to the prompt laboratory diagnosis of TRALI: a case report

OBJECTIVES

Transfusion-related acute lung injury (TRALI) is a rare but serious complication which can occur after transfusion of blood components. In this report we describe our flow-cytometry approach to the laboratory diagnosis of a case of TRALI in a recipient of fresh frozen plasma containing human leukocyte antigen (HLA) class II antibodies.

METHODS

The post-transfusion reaction work-up included the direct and indirect Granulocyte Immunofluorescence Test (GIFT) on the recipient's neutrophils collected before and after the reaction and on the serum from the recipient and from all implicated donors; flow-cytometry bead-based screening and identification assay for HLA class I and II antibodies in donor sera and flow cytometry cross-matching on T and B patient's lymphocytes. Finally, we investigated the reactivity of one donor serum, containing HLA class II antibodies, with the patient's neutrophils activated in vitro to induce expression of HLA class II.

RESULTS

We found an increased level of IgG bound on patient's granulocytes collected after TRALI, in the absence of detectable granulocyte and HLA class I antibodies in the five implicated donors. One of them showed HLA-DR 1 and -DR 51 antibodies, which determined a positive cross-match with patient's B lymphocytes and in vitro activated granulocytes. Both HLA class II antigens were present in the recipient and absent in the donor.

CONCLUSIONS

In some pathological conditions, HLA class II antibodies can react with activated granulocytes expressing HLA-DR antigens, and activate TRALI reaction. HLA class II antibodies screening and flow cytometry cross-matching techniques should be added to the current diagnostic algorithm of TRALI.

Pulmonary injury from transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) can be a life-threatening complication of transfusion. In its severe form, it is clinically indistinguishable from acute respiratory distress syndrome. Symptoms typically begin within 4 hours of transfusion. TRALI has been reported after transfusion of all plasma-containing blood components. TRALI is associated with antibodies to white blood cells and biologically active lipids in trans-fused blood components.

Transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is an uncommon complication of allogeneic blood transfusion manifested typically by shortness of breath, fever, and hypotension. It has been estimated to occur in 0.04% to 0.16% per patient transfused. TRALI has been identified as an important cause of transfusion-related morbidity and mortality. Despite the increasing recognition that TRALI represents an important clinical syndrome, much about the pathogenesis, treatment, and prevention of TRALI is poorly understood or is controversial. In this report, what is known about TRALI is summarized and some of the areas in which knowledge and/or consensus are currently lacking are identified.

Transfusion-related acute lung injury during plasma exchange: Suspecting the unsuspected

Transfusion-related acute lung injury (TRALI) has been implicated with use of almost all types of blood products that contain variable amounts of plasma. Even though the reported incidence of TRALI is rare, its overall occurrence is thought to be more common, as less severe cases remain unreported. More TRALI cases are unrecognized and misdiagnosed due to lack of suspicion and absence of appropriate investigation. There are exceedingly rare reports of TRALI during plasma exchange despite the fact that liters of plasma may be used for replacement during a single procedure. We describe a mild case of TRALI during plasma exchange for thrombotic thrombocytopenic purpura in a 56-year-old woman, status post autologous hematopoietic stem cell transplant for non-Hodgkin's lymphoma. She developed severe rigors, peripheral cyanosis, hypoxia, and a transient diffuse pulmonary infiltrate. Of the 10 U of plasma used, one was from a multiparous female donor with HLA antibodies reactive with patient's granulocytes in immunofluorescence and agglutination assays. This case emphasizes the fact that the physicians and apheresis staff should consider TRALI in the differential diagnosis for patients developing respiratory distress during or soon after the procedure. Diagnosing TRALI has implications not only for the plasma exchange recipient, but also for the management of donors found to have leukocyte antibodies.

16. Immunologic lung disease

This review summarizes the recent advances regarding pathogenesis, diagnosis, and treatment of immunological diseases of the lung. Rather than attempt a comprehensive analysis, we have focused on selected diseases that are of particular relevance to the practicing physician, and the material has been organized according to the dominant immunologic mechanisms underlying the disease. Because of the redundancy that characterizes the mammalian immune repertoire, this system of classification inevitably produces overlap but facilitates acquisition of what is otherwise a disparate collection of facts. The principal lung immunologic mechanisms are most broadly classified as innate or adaptive immune processes. Innate immunity includes neutrophils and complement that are important in diseases, such as pneumonia and the acute respiratory distress syndrome. Adaptive immunity involves T and B cells capable of recognizing discrete antigens. T(H)1- and T(H)2-dependent adaptive immune responses underlie some of the most common and important of lung diseases, including tuberculosis and asthma, respectively. Other important immunopathologic processes include granulomatous inflammation that characterizes sarcoidosis and Churg-Strauss vasculitis, and autoimmunity, which is characteristic of antiglomerular basement membrane disease and others.