Transfusion-associated microchimerism: a new complication of blood transfusions in severely injured patients

Fresh whole blood: A feasible alternative in disasters and mass casualty incidents? a systematic review and meta-analysis

INTRODUCTION

While balanced blood component therapy (BCT) is pivotal in trauma patient damage control resuscitation in well-resourced settings, disasters, and mass casualty incidents (MCIs) pose significant challenges, especially in securing sufficient access to blood products. This systematic review and meta-analysis aim to explore the utilization of fresh whole blood (FWB) transfusion as a potential alternative to BCT, informing future research and clinical strategies.

METHODS

We searched Pubmed, MEDLINE, Embase, CINAHL, the Cochrane Library and grey literature for articles identifying FWB transfusions, limited to those published in English or French. We evaluated the outcomes of post-FWB transfusion and conducted a meta-analysis comparing overall mortality in patients receiving FWB in addition to BCT during damage control resuscitation with those receiving BCT or single blood components alone.

RESULTS

Of the 4830 studies identified, only 74 articles met all the eligibility criteria; the majority of them were conducted in military contexts. Mortality was lower among the FWB group compared to the BCT alone group, with a pooled OR of 0.61 (95% CI: 0.38-0.98) overall, and a pooled OR of 0.47 (95% CI: 0.25-0.87) among studies adjusting for confounders. FWB transfusion related complications rarely occurred.

CONCLUSIONS

While FWB shows potential as an alternative to BCT for managing severe haemorrhagic shock in disasters and MCIs, additional research is essential to validate FWB's efficacy before considering it as a standard approach in civilian scenarios. Further studies focusing on the feasibility of implementing FWB in civilian contexts are also warranted.

The incidence of donor white blood cell survival (transfusion-associated microchimerism) in Australian pediatric patients

INTRODUCTION

Donor leucocyte survival following red blood cell (RBC) transfusion, known as transfusion-associated microchimerism (TAM), can occur in some patients. In Australia, despite the introduction of leucocyte filtration (leucodepletion) during RBC manufacture, TAM has been detected in adult trauma patients. However, the incidence of TAM in Australian pediatric patients has not been analyzed.

METHODS

Patients aged 0-16 years were recruited across two cohorts. Retrospective participants had RBC transfusion between January 1, 2002 and November 15, 2017 and prospective participants received RBC transfusion between December 1, 2016 and November 25, 2020. Twelve bi-allelic insertion/deletion (InDel) polymorphisms were used to detect microchimerism amplification patterns using real-time PCR (RT-PCR) and droplet digital PCR (ddPCR).

RESULTS

Of the retrospective cohort (n = 40), six patients showed amplification of InDel sequences indicating potential microchimerism. For three patients, minor InDel sequences were detected using RT-PCR only, two patients had minor InDel amplification using ddPCR only, and one patient had minor InDel amplification that was confirmed using both techniques. Amplification of minor sequences occurred in three patients who had received a bone marrow transplant in addition to RBC transfusion. In the prospective cohort (n = 25), no InDel amplification indicating potential microchimerism was detected using RT-PCR.

DISCUSSION

Cell-based therapies had been administered in three patients where microchimerism amplification patterns were detected. Three patients have microchimerism that may be attributed to RBC transfusion. In prospective patients, who received leucodepleted and gamma-irradiated RBC units, no potential microchimerism amplification were detected. ddPCR may be a suitable technique for TAM analysis but requires further evaluation.

Use of Low-Titer O-Positive Whole Blood in Female Trauma Patients: A Literature Review, Qualitative Multidisciplinary Analysis of Risk/Benefit, and Guidelines for Its Use as a Universal Product in Hemorrhagic Shock

BACKGROUND

Whole blood transfusion is associated with benefits including improved survival, coagulopathy, and decreased transfusion requirements. The majority of whole blood transfusion is in the form of low-titer O-positive whole blood (LTOWB). Practice at many trauma centers withholds the use of LTOWB in women of childbearing potential due to concerns of alloimmunization. The purpose of this article is to review the evidence for LTOWB transfusion in female trauma patients and generate guidelines for its application.

STUDY DESIGN

Literature and evidence for LTOWB transfusion in hemorrhagic shock are reviewed. The rates of alloimmunization and subsequent obstetrical outcomes are compared to the reported outcomes of LTOWB vs other resuscitation media. Literature regarding patient experiences and preferences in regards to the risk of alloimmunization is compared to current trauma practices.

RESULTS

LTOWB has shown improved outcomes in both military and civilian settings. The overall risk of alloimmunization for Rhesus factor (Rh) - female patients in hemorrhagic shock exposed to Rh + blood is low (3% to 20%). Fetal outcomes in Rh-sensitized patients are excellent compared to historical standards, and treatment options continue to expand. The majority of female patients surveyed on the risk of alloimmunization favor receiving Rh + blood products to improve trauma outcomes. Obstetrical transfusion practices have incorporated LTOWB with excellent results.

CONCLUSIONS

The use of whole blood resuscitation in trauma is associated with benefits in the resuscitation of severely injured patients. The rate at which severely injured, Rh-negative patients develop anti-D antibodies is low. Treatments for alloimmunized pregnancies have advanced, with excellent results. Fears of alloimmunization in female patients are likely overstated and may not warrant the withholding of whole blood resuscitation. The benefits of whole blood resuscitation likely outweigh the risks of alloimmunization.

What is the Role of Whole Blood Transfusions on Trauma Patients?

Whole blood use in trauma has historically been limited to military use, but in recent years, there has been increasing data for use in civilian trauma. Emerging clinical data demonstrate an associated survival benefit, while some authors have also identified decreased use of an overall number of blood products and decreased complications. Use of whole blood is gradually moving toward becoming the standard of care in the hemorrhaging trauma patient.

Microchimerism as Post-Transplant Marker of a Chronic Rejection Process

The risk of losing a transplanted organ is high, and non-invasive markers to warn of this phenomenon are still being sought. We investigated the impact of post-transplant microchimerism on the function of the transplanted kidney. The study included 100 kidney transplant recipients, mostly women. All transplanted organs were from opposite-sex deceased donors. Microchimerism was assessed using multiplex PCR. Male DNA was detected in all urine samples from female recipients and in 13/56 blood samples from female kidney recipients. Female DNA was found in 31/44 urine samples from male recipients, but in none of the blood samples. Microchimerism in the urine of female recipients correlated positively with blood urea (Rs = 0.45; p = 5.84 × 10^-4) and K⁺ ions (Rs = 0.29; p = 0.03), while microchimerism in the blood of female recipients also correlated positively with blood urea (Rs = 0. 28; p = 0.04), cystatin C (Rs = 0.31; p = 0.02) and the number of incompatible HLA alleles (Rs = 0.42; p = 0.01). A history of DGF was associated with higher urinary donor DNA concentrations in female recipients.: Post-transplant microchimerism may serve as a potential marker of chronic kidney rejection.

High Frequency of Post-Transfusion Microchimerism Among Multi-Transfused Beta-Thalassemic Patients

Background

Transfusion-associated microchimerism implies the presence of allogeneic hematopoietic cells in an individual, following the transfusion of a blood product. It is a transfusion-related adverse effect/long-term consequence, which has not been well-investigated among regularly transfused patients with thalassemia.

Patients and Methods

We investigated 64 regularly transfused, homozygous β-thalassemic patients and 21 never-transfused healthy volunteer blood donors (controls) for the presence of microchimerism in their sera, using real-time PCR targeting circulating allogeneic, both, Human Leukocyte Antigen-DR isotype (HLA-DR) and non-HLA alleles. The investigation was longitudinally repeated in patient subsets for more than 2 years. Results were correlated with clinical and laboratory parameters, peripheral blood lymphocyte immunophenotype, blood storage time, and donor's gender to identify potential contributing factors for microchimerism generation.

Results

Overall, microchimerism was detected in 52 of the 64 patients (81.2%) and in 6 of the 21 controls (28.5%, p = 0.0001). Forty-four patients (68.7%) exhibited long-term microchimerism (persisted for more than 6 months), confirmed at all time-points investigated. Microchimerism was more frequent among elderly, women, splenectomized and more heavily transfused patients, and among those who exhibit higher serum ferritin levels. In these patients, a distinct descending pattern of CD16^dim+CD56^dim+ natural killer (NK)-cells (p < 0.001) and an ascending pattern of CD4+CD25^brightCD127– regulatory T-cells (p = 0.022) for increasing allelic burden were noticed, suggesting the establishment of recipient immune tolerance against the donor-derived chimeric alleles. Both splenectomized and non-splenectomized thalassemic patients exhibited the same trend. The storage time of transfused blood products and donor/gender mismatch had no impact on the development of microchimerism.

Discussion-Conclusive Remarks

Transfusion-associated microchimerism appears to be a very common complication among multi-transfused thalassemic patients. The potential clinical consequences of this phenomenon remain as yet unclear. Immune tolerance attributed to disease itself and to repeated transfusions might at least in part explain its appearance.

Back to the Future: Whole Blood Resuscitation of the Severely Injured Trauma Patient

ABSTRACT

Following advances in blood typing and storage, whole blood transfusion became available for the treatment of casualties during World War I. While substantially utilized during World War II and the Korean War, whole blood transfusion declined during the Vietnam War as civilian centers transitioned to blood component therapies. Little evidence supported this shift, and recent conflicts in Iraq and Afghanistan have renewed interest in military and civilian applications of whole blood transfusion. Within the past two decades, civilian trauma centers have begun to study transfusion protocols based upon cold-stored, low anti-A/B titer type O whole blood for the treatment of severely injured civilian trauma patients. Early data suggests equivalent or improved resuscitation and hemostatic markers with whole blood transfusion when compared to balanced blood component therapy. Additional studies are taking place to define the optimal way to utilize low-titer type O whole blood in both prehospital and trauma center resuscitation of bleeding patients.

Can RH+ whole blood be safely used as an alternative to RH- product? An analysis of efforts to improve the sustainability of a hospital's low titer group O whole blood program

BACKGROUND

Low-titer group O whole blood (LTO-WB) has recently gained popularity in trauma centers for the acute resuscitation of hemorrhagic shock. However, limited supplies of Rh- product prevent implementation and strain sustainability at many trauma centers. We set out to identify whether Rh+ LTO-WB could be safely substituted for RH- product, regardless of patient's Rh status.

METHODS

Following Institutional Review Board approval, information on all trauma patients receiving prehospital or emergency department transfusion of uncrossed, emergency release LTO-WB (11/17-10/19) were evaluated. Patients were first divided into those who received Rh- versus Rh+ product, the assessed by Rh of the recipient. Serial hemolysis panels, transfusion reactions, and outcomes were compared.

RESULTS

Six hundred thirty-seven consecutive trauma patients received emergency release LTO-WB. Of these, 448 received Rh+ product, while 189 received Rh- LTO-WB. Patients receiving Rh+ product were more likely to be men (81 vs. 70%) and have lower field blood pressure (median 99 vs. 109) and GCS (median 7 vs. 12); all p < 0.05. There were no differences in blood product volume, hemolysis laboratories, transfusion reactions, complications, or survival. We then separated patients by Rh status (577 were Rh+, 70 were Rh-). Rh- patients were older (median age 54 vs. 39), more likely to be women (57 vs. 26%), and more likely to have sustained blunt trauma than their Rh+ counterparts (92 vs. 70%); all p < 0.05. There were no differences in hemolysis laboratories, transfusion reactions, complications, or survival between Rh+ and Rh- patients, regardless of Rh product received.

CONCLUSION

When Rh- whole blood is unavailable or in short supply, Rh+ LTO-WB appears to be a safe alternative for the resuscitation of hemorrhagic shock in both Rh+ and Rh- patients. Use of Rh+ product may help trauma centers incorporate LTO-WB into their hospital and improve sustainability of such programs.

LEVEL OF EVIDENCE

Therapeutic, Level III.

Association between the length of storage of transfused leukoreduced red blood cell units and hospital-acquired infections in critically ill children: A secondary analysis of the TRIPICU study

OBJECTIVE

Evaluate the association between leukoreduced red blood cell (RBC) storage length and hospital-acquired infection (HAI) incidence rate in critically ill children.

BACKGROUND

RBC transfusions are common in critically ill children. Despite their benefits, observational studies suggest an association between them and HAIs. One possible mechanism for increased HAI is transfusion-related immunomodulation due to bioactive substances' release as transfused blood ages.

METHODS

In this secondary analysis of the 'Transfusion Requirement in Paediatric Intensive Care Units' (TRIPICU) study, we analysed a subset of 257 participants that received only one pre-storage leukoreduced RBC transfusion. RBC storage length was classified as 1) transfusion of 'fresh' RBCs (≤10 days), 2) transfusion of 'stored' RBCs (21-34 days), and 3) transfusion of 'long-stored' RBCs (≥35 days). All were compared to a 'golden' period (11-20 days), representing the time between 'fresh' and 'stored'. We used quasi-Poisson multivariable regression models to estimate the HAI incidence rate ratio (IRR) and corresponding 95% confidence interval (CI).

RESULTS

We found that the association between the length of storage time of leukoreduced RBCs and HAIs was not significant in the 'fresh' group (IRR 1.23; 95% CI 0.55, 2.78) and the 'stored' group (IRR 1.61; 95% CI 0.63, 4.13) when compared to the 'golden' period. However, we observed a statistically significant association between the 'long-stored' group and an increase in the HAI incidence rate (IRR 3.66; 95% CI 1.22, 10.98).

CONCLUSION

Transfusion of leukoreduced RBC units stored for ≥35 days is associated with increased HAI incidence rate in haemodynamically stable, critically ill children.

Extracellular DNA in blood products and its potential effects on transfusion

Blood transfusions are sometimes necessary after a high loss of blood due to injury or surgery. Some people need regular transfusions due to medical conditions such as haemophilia or cancer. Studies have suggested that extracellular DNA including mitochondrial DNA present in the extracellular milieu of transfused blood products has biological actions that are capable of activating the innate immune systems and potentially contribute to some adverse reactions in transfusion. From the present work, it becomes increasingly clear that extracellular DNA encompassed mitochondrial DNA is far from being biologically inert in blood products. It has been demonstrated to be present in eligible blood products and thus can be transfused to blood recipients. Although the presence of extracellular DNA in human plasma was initially detected in 1948, some aspects have not been fully elucidated. In this review, we summarize the potential origins, clearance mechanisms, relevant structures, and potential role of extracellular DNA in the innate immune responses and its relationship with individual adverse reactions in transfusion.

A high transfusion burden following an ambulatory-allogeneic hematopoietic cell transplantation using reduced-intensity conditioning is associated with adverse outcomes

OBJECTIVES

Ambulatory allogeneic hematopoietic cell transplantation (allo-HCT) after reduced-intensity conditioning (RIC) is a cost-effective option for hematology patients. Data on the impact of transfusion burden in this setting are scarce; we analyzed this retrospectively.

METHODS

A study of 177 HLA-identical and haploidentical allo-HCT recipients on an outpatient basis was conducted between 2013 and 2019. Packed red blood cell (PRBC) and platelet transfusions were documented from days 0-100 after HCT.

RESULTS

A total of 121 patients (68.4%) required transfusion while 56 (31.6%) did not. In the multivariate analysis, a lower disease-free (DFS) and overall survival (OS) were documented for patients that received ≥9 total blood products (p = 0.018) (p = 0.014), those who required hospitalization (p = 0.001) (p < 0.001), had acute graft-versus-host disease (p = 0.016) (p = 0.004), and a high/very high Disease-Risk-Index (p = 0.002; p = 0.004), respectively. Transfusion of ≥5 PRBC units was associated with a lower OS (p = 0.027). The cumulative incidence of transplant-related mortality at two years for an HLA-identical transplant was 9.5% and for haploidentical, it was 27.1% (p = 0.027); this last group had significantly more transfusion demands than HLA-identical recipients (p = 0.029).

CONCLUSION

Increased blood product utilization is an independent predictor of decreased survival in ambulatory RIC allo-HCT recipients. Further evidence leading to individualized guidelines to transfuse in this complex scenario is needed.

Implications of perioperative allogeneic red blood cell transfusion on the immune-inflammatory response

Background

The allogeneic transfusion-related immunomodulation (TRIM) may be responsible for an increase in survival of renal transplants but in contrast it could increase the rate of bacterial infections or the recurrence rate of tumors post-operatively.

Objective

This review focuses in the implications of perioperative allogeneic transfusions on the immune-inflammatory response of surgical transfused patients.

Results

ABTs modify immune functions in recipients including decrease of the number of lymphocytes; decrease the CD4 cells; decrease the CD4/CD8 T-cell ratio; decrease NK cells; and decrease the lymphocyte response to mitogens. TRIM effects may be mediated by allogeneic white cells present in blood products; soluble peptides present in transfused plasma; and/or biologic mediators released into the supernatant of blood units. A recent systematic review and meta-analysis including 36 clinical observational studies (n = 174,036) concluded that perioperative ABTs not only decreased overall survival and reduced colorectal cancer-specific survival. Furthermore ABTs increased the rate of infectious, cardiac, pulmonary and anastomotic complications in colorectal cancer patients undergoing surgery.

Conclusions

It has been demonstrated by laboratory tests that TRIM is associated with transfusion recipient immune alterations but its influence in colorectal cancer recurrence after resection remains controversial though may exist. Surgical techniques reducing intraoperative blood loss have limited the number of ABTs perioperatively, however increase in mortality continues to be reported in literature after ABT in colorectal cancer surgery. Poor survival associated to TRIM in colorectal cancer might be due to higher number of allogeneic transfused units and/or prolonged length of blood storage.

Damage control resuscitation

The United States Navy originally utilized the concept of damage control to describe the process of prioritizing the critical repairs needed to return a ship safely to shore during a maritime emergency. To pursue a completed repair would detract from the goal of saving the ship. This concept of damage control management in crisis is well suited to the care of the critically ill trauma patient, and has evolved into the standard of care. Damage control resuscitation is not one technique, but, rather, a group of strategies which address the lethal triad of coagulopathy, acidosis, and hypothermia. In this article, we describe this approach to trauma resuscitation and the supporting evidence base.

Immunogenicity of a rheumatoid arthritis protective sequence when acquired through microchimerism

HLA class II genes provide the strongest genetic contribution to rheumatoid arthritis (RA). HLA-DRB1 alleles encoding the sequence DERAA are RA-protective. Paradoxically, RA risk is increased in women with DERAA⁺ children born prior to onset. We developed a sensitive qPCR assay specific for DERAA, and found 53% of DERAA^-/- women with RA had microchimerism (Mc; pregnancy-derived allogeneic cells) carrying DERAA (DERAA-Mc) vs. 6% of healthy women. DERAA-Mc quantities correlated with an RA-risk genetic background including DERAA-binding HLA-DQ alleles, early RA onset, and aspects of RA severity. CD4⁺ T cells showed stronger response against DERAA⁺ vs. DERAA^- allogeneic cell lines in vitro, in line with an immunogenic role of allogeneic DERAA. Results indicate a model where DERAA-Mc activates DERAA-directed T cells that are naturally present in DERAA^-/- individuals and can have cross-reactivity against joint antigens. Moreover, we provide an explanation for the enigmatic observation that the same HLA sequence differentially affects RA risk through Mendelian inheritance vs. microchimeric cell acquisition.

Screw view model of navigation in posterior corrective surgery for adolescent idiopathic scoliosis: A case report and technique note

RATIONALE

The purpose of this study is to introduce the application of screw view model of navigation (SVMN) for adolescent idiopathic scoliosis (AIS). It is a challenge to insert pedicle screw into the vertebral body of scoliosis, and the misplaced screw may lead to neurovascular injury. In order to minimize surgical complications, we used a novel method of SVMN technology to facilitate pedicle screw insertion.

PATIENT CONCERNS

Her mother brought her to our outpatient department upon noticing the girl's different heights of shoulders and unbalance of the trunk.

DIAGNOSES

She was diagnosed with AIS and syringomyelia.

INTERVENTIONS

We used an SVMN technology to assist pedicle screw insertion and correction surgery in this 20-year-old patient.

OUTCOMES

This study indicates that the SVMN could obtain a satisfactory surgical effect for AIS. The Cobb angle of segmental scoliosis (T7-L2) was 55° before surgery, and 3.5° after surgery, and the rate of correction was 93.6%. The segmental kyphosis (T7-L1) was 56.8° preoperatively and 32° postoperatively with the rate of correction of 43.6%. The distance between the center sacral vertical line (CSVL) and the C7 plumb line (CPL) was reduced from 56.2 mm to 0.2 mm, and the sagittal imbalance of 35.8 mm was improved to 3.5 mm. In addition, the misplacement of pedicle screws, the volume of blood loss, the operation time, and surgical complications were also recorded. The follow-up duration was 33 months.

LESSONS

The utilization of SVMN in AIS might reduce the incidence of screw misplacement and avoid neurovascular damage, as well as a satisfactory correction. The application of SVMN for AIS is an efficacious and safe method.

Donor white blood cell survival and cytokine profiles following red blood cell transfusion in Australian major trauma patients

BACKGROUND

The potential for the co-existence of genetically disparate cells (microchimerism) and associated cytokine profiles following red blood cell (RBC) transfusion in trauma patients has not been well characterized to date. This study investigated the incidence of surviving donor white blood cells (known as transfused-associated microchimerism (TAM)) and cytokine changes following blood transfusion in trauma patients.

STUDY DESIGN AND METHODS

Trauma patients with an injury severity score (ISS) >12 who had been transfused between 2012-2016 with at least 5 units of RBC units over a 4 h period were recruited. Trauma patients with ISS > 12 who did not require blood transfusion were recruited as controls. The incidence of TAM was determined using a panel of insertion/deletion (InDel) bi-allelic polymorphisms. Selected pro- and anti-inflammatory cytokine profiles were analyzed using cytometric bead array.

RESULTS

The transfused cohort (n = 40) had median ISS of 28 [12-66], received a median of 11 RBC units [4-114] and had median hospital length of stay of 35 days [1-152]. Only 11 (27.5%) patients returned for follow-up blood sampling after discharge. Of these, one patient showed an InDel pattern indicating the presence of TAM. No patients in the control cohort (n = 49) showed TAM. Cytokines IL-10 and IL-6 were found to be elevated in the transfused trauma patients.

CONCLUSION

In this cohort, TAM was found to occur in one patient of the 11 who received a blood transfusion. Elevated IL-6 and IL-10 cytokines were detected in those patients who were transfused. However, the incidence of TAM could not be correlated with the elevated cytokine profiles for this cohort.

Mechanisms of red blood cell transfusion-related immunomodulation

Red blood cell (RBC) transfusion is common in critically ill, postsurgical, and posttrauma patients in whom both systemic inflammation and immune suppression are associated with adverse outcomes. RBC products contain a multitude of immunomodulatory mediators that interact with and alter immune cell function. These interactions can lead to both proinflammatory and immunosuppressive effects. Defining clinical outcomes related to immunomodulatory effects of RBCs in transfused patients remains a challenge, likely due to complex interactions between individual blood product characteristics and patient-specific risk factors. Unpacking these complexities requires an in-depth understanding of the mechanisms of immunomodulatory effects of RBC products. In this review, we outline and classify potential mediators of RBC transfusion-related immunomodulation and provide suggestions for future research directions.

Male microchimerism in peripheral blood leukocytes from women with multiple sclerosis

BACKGROUND

Fetal microchimerism (F-MC), the persistence of fetal cells in the mother, is frequently encountered following pregnancy. The high prevalence of F-MC in autoimmune disease prompts consideration of the role for immune tolerance and regulation. This study examines the association between F-MC and multiple sclerosis (MS), an autoimmune disorder, of undetermined etiology.

RESULTS

21 out of 51 MS-positive subjects (41%) were classified as positive for F-MC; 4 of 22 (18%) of MS-negative sibling controls, were also positive for MC (p = 0.066). Unanticipated F-MC in controls lead to re-evaluation using 30 female singleton cord blood units (CBUs) as a biological control. Four CBUs were low-level positive.

STUDY DESIGN AND METHODS

Seventy-three female subjects were assigned to three groups according to disease status and pregnancy history: (1) MS positive (+) women with a history of one male pregnancy before symptom onset (n = 27); (2) MS negative (-) female siblings of MS(+) women with a history of one male pregnancy (n = 22); and (3) MS(+) women that reported never having been pregnant (n = 24). Ten micrograms of genomic DNA obtained from peripheral blood leukocytes of each subject were analyzed for F-MC using allele-specific real-time PCR targeting the SR-Y sequence on the Y-chromosome. MC classification was dichotomous (positive vs. negative) based on PCR results.

CONCLUSION

The association between F-MC and MS warrants further study to define this relationship. F-MC in women self-reporting as nulligravid, supports previous findings that a significant proportion of pregnancies go undetected. This lead to re-validation of a Y-chromosome based assay for F-MC detection.

Engineering Therapeutic T Cells: From Synthetic Biology to Clinical Trials

Engineered T cells are currently in clinical trials to treat patients with cancer, solid organ transplants, and autoimmune diseases. However, the field is still in its infancy. The design, and manufacturing, of T cell therapies is not standardized and is performed mostly in academic settings by competing groups. Reliable methods to define dose and pharmacokinetics of T cell therapies need to be developed. As of mid-2016, there are no US Food and Drug Administration (FDA)-approved T cell therapeutics on the market, and FDA regulations are only slowly adapting to the new technologies. Further development of engineered T cell therapies requires advances in immunology, synthetic biology, manufacturing processes, and government regulation. In this review, we outline some of these challenges and discuss the contributions that pathologists can make to this emerging field.

Microchimerism of male origin in a cohort of Danish girls

Male microchimerism, the presence of a small number of male cells, in women has been attributed to prior pregnancies. However, male microchimerism has also been reported in women with only daughters, in nulliparous women and prepubertal girls suggesting that other sources of male microchimerism must exist. The aim of the present study was to examine the presence of male microchimerism in a cohort of healthy nulliparous Danish girls aged 10-15 y using DNA extracted from cells from whole blood (buffy coats) and report the association with potential sources of male cells. A total of 154 girls were studied of which 21 (13.6%) tested positive for male microchimerism. There was a tendency that girls were more likely to test positive for male microchimerism if their mothers previously had received transfusion, had given birth to a son or had had a spontaneous abortion. Furthermore, the oldest girls were more likely to test positive for male microchimerism. However, less than half of microchimerism positivity was attributable to these factors. In conclusion, data suggest that male microchimerism in young girls may originate from an older brother either full born or from a discontinued pregnancy or from transfusion during pregnancy. We speculate that sexual intercourse may be important but other sources of male cells likely exist in young girls.

Leukodepleted blood components do not remove the potential for long-term transfusion-associated microchimerism in Australian major trauma patients

Despite the introduction of leukodepleted blood components, it has been shown that donor leukocyte engraftment (microchimerism) remains a long-term consequence of red blood cell (RBC) transfusion. The incidence of microchimerism may be affected by international disparities in blood processing methods or variations in transfusion practices. This study was conducted to determine the prevalence of microchimerism in Australian trauma patients. A secondary aim was to examine whether any patient complications correlated to the incidence of microchimerism. Australian trauma patients (n = 86) who had been transfused with red blood cell (RBC) units between 2000 and 2012 with an injury severity score (ISS) of greater than 15 were recruited. The prevalence of microchimerism was determined using genetic screening with a panel of insertion/deletion biallelic polymorphisms. The mean storage age of the transfused RBC units was 20 ± 8 days and the mean length of stay (LOS) in hospital was 40 ± 39 days. There were no significant associations in this study sample to bias for patient age, gender, number of transfused RBC units or ISS. Nine of the 55 (16.3%) patients transfused with non-leukodepleted blood components displayed an incidence of microchimerism. Of the 31 patients transfused with leukodepleted RBC units, 3 (9.6%) displayed an incidence of microchimerism. Therefore, despite the universal introduction of leukodepleted blood components in Australia, the prevalence of transfusion-associated microchimerism was found to be unchanged. Furthermore, half of the patients exhibiting microchimerism were recorded to have had splenic injury or required splenectomy at the time of transfusion.

Pediatric transplantation and tolerance: past, present, and future

Solid organ transplantation is the treatment of choice in children with end-stage organ failure. With improving methods of transplant surgery and post-transplant care, transplantation is more frequently performed worldwide. However, lifelong and non-specific suppression of the recipient's immune system is a cause of significant morbidity in children, including infection, diabetes, and cancer. There is a great need to develop IS minimization/withdrawal and tolerance induction approaches.

Gamma irradiation preserves immunosuppressive potential and inhibits clonogenic capacity of human bone marrow-derived mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) are promising candidates for the treatment of graft-versus-host and autoimmune diseases. Here, by virtue of their immunosuppressive effects, they are discussed to exhibit inhibitory actions on various immune effector cells, including T lymphocytes that promote the underlying pathology. While it becomes apparent that MSCs exhibit their therapeutic effect in a transient manner, they are usually transplanted from third party donors into heavily immunocompromised patients. However, little is known about potential late complications of persisting third party MSCs in these patients. We therefore analysed the effect of gamma irradiation on the potency and proliferation of MSCs to elucidate an irradiation dose, which would allow inhibition of MSC proliferation while at the same time preserving their immunosuppressive function. Bone marrow-derived MSCs (BM-MSCs) were gamma-irradiated at increasing doses of 5, 10 and 30 Gy and subsequently assessed by colony formation unit (CFU)-assay, Annexin V-staining and in a mixed lymphocyte reaction, to assess colony growth, apoptosis and the immunosuppressive capacity, respectively. Complete loss of proliferative capacity measured by colony formation was observed after irradiation with a dose equal to or greater than 10 Gy. No significant decrease of viable cells was detected, as compared to non-irradiated BM-MSCs. Notably, irradiated BM-MSCs remained highly immunosuppressive in vitro for at least 5 days after irradiation. Gamma irradiation does not impair the immunosuppressive capacity of BM-MSCs in vitro and thus might increase the safety of MSC-based cell products in clinical applications.

Comparative sensitivity analyses of quantitative polymerase chain reaction and flow cytometry in detecting cellular microchimerism in murine tissues

Cellular microchimerism is defined as the presence of small populations of cells from one individual in another genetically distinct individual. The pivotal role of cellular microchimerism in a variety of immune settings is increasingly recognized, e.g. in context of pregnancy, transplantation and cancer. However, the detection of chimeric cells is overshadowed by technical limitations. This study aimed to overcome these limitations by testing the sensitivity and detection limit of a molecular biology approach (quantitative polymerase chain reaction, qPCR) and a cellular approach (flow cytometry) in order to identify experimentally induced cellular microchimerism in mice. Leukocytes isolated from lymph nodes or spleens of transgenic enhanced green fluorescent protein (eGFP) and CD45.1 mice respectively were used as targets to be detected as microchimeric cells among wild type (wt) or haploidentical cells. The detection limit of microchimeric cells by flow cytometry was 0.05% or lower for the respective eGFP(+) or CD45.1(+) cell subsets, which equals 48 cells or fewer per 1×10(5) wt cells. The detection limit of CD45.1(+) and CD45.2(+) cells among haploidentical CD45.1(+)2(+) cells by flow cytometry was 48 cells (0.05%) and 198 cells (0.2%), respectively. Using qPCR, a detection limit of 198 eGFP(+) cells per 1×10(5) wt cells, respective 0.2%, could be achieved. We here introduce two technical approaches to reliably detect low number of chimeric cells at a low detection limit and high sensitivity in transgenic mouse systems.

Fetal-maternal interface: a chronicle of allogeneic coexistence

The existence of allogeneic cells within an individual has been demonstrated in multiple fields such as hematopoietic stem cell or solid organ transplantation, non-depleted blood transfusions and the most common form which is bidirectional maternal-fetal cell trafficking, whereby cells from the fetus pass through the placental barrier. In order to graphically illustrate this early natural phenomenon that initiates the journey of a child’s cells within the mother’s blood and other tissues, we used a new procedure in microscopy imaging generating Large Scale Panoramic Pictures (LSPP). This technique can also be extended to explore a broad diversity of experimental models.

Transfusion-associated microchimerism: the hybrid within

Microchimerism, the coexistence of genetically disparate populations of cells in a receptive host, is well described in both clinical and physiological settings, including transplantation and pregnancy. Microchimerism can also occur after allogeneic blood transfusion in traumatically injured patients, where donor cells have been observed decades after transfusion. To date, transfusion-associated microchimerism (TA-MC) appears confined to this clinical subset, most likely due to the immune perturbations that occur after severe trauma that allow foreign donor cells to survive. Transfusion-associated microchimerism appears to be unaffected by leukoreduction and has been documented after transfusion with an array of blood products. The only significant predictor of TA-MC to date is the age of red cells, with fresher units associated with higher risk. Thus far, no adverse clinical effect has been observed in limited studies of TA-MC. There are, however, hypothesized links to transfusion-associated graft vs host disease that may be unrecognized and consequently underreported. Microchimerism in other settings has gained increasing attention owing to a plausible link to autoimmune diseases, as well as its diagnostic and therapeutic potential vis-a-vis antenatal testing and adoptive immunotherapy, respectively. Furthermore, microchimerism provides a tool to further our understanding of immune tolerance and regulation.

Factors associated with acute lung injury in combat casualties receiving massive blood transfusions: a retrospective analysis

PURPOSE

We sought to determine if use of warm fresh whole blood (WFWB), rather than blood component therapy, alters rates of acute lung injury (ALI) in patients with trauma.

MATERIALS AND METHODS

We retrospectively analyzed rates of ALI in patients undergoing massive blood transfusions while at a combat support hospital. Patients with ALI were compared with those not developing ALI with respect to demographics, trauma type, severity of illness, crystalloid volume given, and exposure to WFWB. Logistic regression was used to identify variables associated with ALI.

RESULTS

The cohort included 591 subjects (mean age, 28 ± 8.1 years; male, 96.7%). Acute lung injury occurred in 11.2%, and 34.4% received WFWB. After adjusting for the type of trauma, severity of illness, and volume of crystalloid administered, WFWB remained independently associated with ALI (adjusted odds ratio [AOR], 1.06; 95% confidence interval [CI], 1.00-1.13). Nearly two thirds of persons with ALI never received WFWB; factors associated with the use of WFWB were also examined. Severity of illness (AOR, 1.18; 95% CI, 1.02-1.35), crystalloid volume (AOR, 1.12; 95% CI, 1.06-1.18), recombinant factor VIIa use (AOR, 1.94; 95% CI, 1.06-3.57), and US citizenship (AOR, 3.06; 95% CI, 1.74-5.37) correlated with WFWB use.

CONCLUSIONS

Warm fresh whole blood may be associated with an increased risk of ALI, but this is confounded by increased injury and crystalloid use in patients receiving WFWB.

Antigenic challenge in the etiology of autoimmune disease in women

Infection has long been implicated as a trigger for autoimmune disease. Other antigenic challenges include receipt of allogeneic tissue or blood resulting in immunomodulation. We investigated antigenic challenges as possible risk factors for autoimmune disease in women using the Health and Retirement Study, a nationally representative longitudinal study, linked to Medicare files, years 1991-2007. The prevalence of autoimmune disease (rheumatoid arthritis, Hashimoto's disease, Graves' disease, systemic lupus erythematosus, celiac disease, systemic sclerosis, Sjögren syndrome and multiple sclerosis) was 1.4% in older women (95% CI: 1.3%, 1.5%) with significant variation across regions of the United States. The risk of autoimmune disease increased by 41% (95% CI of incidence rate ratio (IRR): 1.10, 1.81) with a prior infection-related medical visit. The risk of autoimmune disease increased by 90% (95% CI of IRR: 1.36, 2.66) with a prior transfusion without infection. Parity was not associated with autoimmune disease. Women less than 65 years of age and Jewish women had significantly elevated risk of developing autoimmune disease, as did individuals with a history of heart disease or end-stage renal disease. Antigenic challenges, such as infection and allogeneic blood transfusion, are significant risk factors for the development of autoimmune disease in older women.

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.

The plasma fraction of stored erythrocytes augments pancreatic cancer metastasis in male versus female mice

BACKGROUND

Males with pancreatic cancer have decreased survival compared with females. Interestingly, perioperative blood transfusions have been shown to reduce survival in patients with pancreatic adenocarcinoma. Recent evidence incriminates blood transfusions from female donors as a causative factor in acute lung injury. We therefore hypothesize that male mice with pancreatic cancer will have greater tumor progression than female mice in response to transfusion.

METHODS

Mice previously inoculated with pancreatic cancer cells received an intravenous injection of acellular plasma collected from single donor erythrocytes from either male or female donors. Control mice received an equal volume of intravenous saline. Necropsy to determine metastasis was performed in female mice at 4 wk status post-transfusion. The male group necessitated sacrifice at 3 wk post-transfusion due to clinical deterioration.

RESULTS

Male mice developed more metastatic events than female mice, and this was accentuated when receiving blood from female donors. Male mice experienced weight loss within 2 wk of tail vein injection, and three mice in the male transfused groups died secondary to malignancy. Female mice did not manifest substantial weight loss, and did not die in the study time period.

CONCLUSION

Male mice, compared with female, had significantly more metastatic events following transfusion of plasma from stored erythrocytes in an immunocompetent murine model of pancreatic adenocarcinoma. Moreover, the adverse effect of transfusion was augmented with female donor blood. These data are consistent with clinical outcomes from centers of excellence in treating pancreatic cancer and warrant further investigation.

Should microchimerism turn into rejection prophylactics?

Non-self cells can circulate in the body of an individual after any sort of contact with an allogeneic source of cells, thus creating a situation of chimerism that can be transient or prolonged over time. This situation may appear after stem cell transplantation, pregnancy, transfusion or transplantation. Concerning transplantation, many hypotheses have been formulated regarding the existence, persistence and role of these circulating cells in the host. We will review the principal hypotheses that have been formulated for years since the first description of non-self circulating cells in mammals to the utilization of artificially induced chimerism protocols for the achievement of tolerance.

The importance of Foxp3 antibody and fixation/permeabilization buffer combinations in identifying CD4+CD25+Foxp3+ regulatory T cells

Foxp3 is a key marker for CD4(+) regulatory T cells (T(regs)) and was used in developing a multiparameter flow cytometric panel to identify T(regs). Achieving reproducible staining and analysis first required optimization of Foxp3 staining. We present a comparative study of PCH101, 236A/E7, 3G3, 206D, 150D, and 259D/C7 clones of anti-human-Foxp3 antibodies used in combination with five different fixation/permeabilization buffers. Staining for CD25, CD152, and CD127 was also compared between fixation/permeabilization treatments. Promising antibody/buffer combinations were tested in a panel of peripheral blood mononuclear cells from 10 individuals, and then on fresh versus frozen cells from four individuals. Finally, different fluorochromes coupled to two representative antibodies were compared to optimize separation of Foxp3(+) from Foxp3(-) events. Foxp3 gates were set using two gating strategies based on CD127(+)CD25(-) "non-T(regs)" or based on isotype controls. For Foxp3 staining, the best conditions for fixation/permeabilization were obtained using the eBioscience Foxp3, Imgenex, BioLegend, and BD Foxp3 buffers. Comparing results from 10 subjects, 259D/C7, PCH101, 236A/E7, and 206D antibodies yielded statistically higher levels of Foxp3 cells than those by 150D and 3G3 antibodies (mean = 6.9, 5.1, 4.7, and 3.7% compared with 1.7, and 0.3% of CD25(+)Foxp3(+) events within CD4(+) cells, respectively). Importantly, the "nonspecificity" of some antibodies observed with a Foxp3 gate based on isotype controls could be eliminated by setting the Foxp3 gate on "non-T(regs)". Better separation of Foxp3(+) and Foxp3(-) populations was observed using the PCH101 clone coupled to Alexa647 compared with FITC or the 259D/C7 clone coupled to PE compared with Alexa488 fluorochrome. Foxp3 staining can be highly variable and depends on the choice of antibody/buffer pair and the fluorochrome used. Selecting the correct population for setting the Foxp3 gate is critical to avoid including non-T(regs) in the Foxp3(+) gate. The experiments presented here will aid in optimization of flow cytometry staining panels to quantify T(reg) frequencies in humans.

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

BACKGROUND

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

STUDY DESIGN AND METHODS

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

RESULTS

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

CONCLUSION

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

Does a febrile reaction to platelets predispose recipients to red blood cell alloimmunization?

BACKGROUND

A variable effect of inflammation on alloimmunization to transfused red blood cells (RBCs) in mice has been recently reported. We investigated whether RBC alloimmunization in humans was affected by transfusion of blood products in temporal proximity to experiencing a febrile transfusion reaction (FTR) to platelets (PLTs), an event predominantly mediated by inflammatory cytokines.

STUDY DESIGN AND METHODS

Blood bank databases were used to identify patients who experienced an FTR or possible FTR to PLTs from August 2000 to March 2008 (FTR group). The control group of patients received a PLT transfusion on randomly selected dates without experiencing an FTR. The "event" was defined as the PLT transfusion that caused the FTR in the FTR group or the index PLT transfusion in the control group. The number of transfused blood products and their proximity to the event were recorded along with other recipient data. The primary endpoint was the rate of RBC alloimmunization between the two groups.

RESULTS

There were 190 recipients in the FTR group and 245 in the control group. Overall, the recipients in the control group were younger and received more blood products on the day of their event and over the subsequent 10 days. The alloimmunization rate among recipients in the FTR group was higher than in the control group (8% vs. 3%, respectively; p = 0.026).

CONCLUSIONS

These preliminary data support our hypothesis that recipient inflammation may affect RBC alloimmunization in humans; however, a more detailed understanding of the pathophysiologic association between inflammation and alloimmunization is required before definitive conclusions can be reached.

Transfusion associated microchimerism: a heretofore little-recognized complication following transfusion

Potent antiplatelet and antithrombotic agents have significantly reduced mortality in the setting of acute coronary syndromes and percutaneous coronary intervention. However these agents are associated with increased bleeding which is in turn associated with adverse clinical outcomes. In many centers, transfusion is often used to correct for blood loss. Blood transfusion in the setting of acute coronary syndrome has been associated with adverse clinical outcomes including increased mortality. Transfusion associated microchimerism (TA-MC) is a newly recognized complication of blood transfusion. There is engraftment of the donor's hematopoietic stem cells in patients who then develop microchimerism. This article discusses the association of bleeding/blood transfusion with adverse outcomes and the potential role of TA-MC in clinical outcomes.

Plasticity after allogeneic hematopoietic stem cell transplantation

The postulated almost unlimited potential of transplanted hematopoietic stem cells (HSCs) to transdifferentiate into cell types that do not belong to the hematopoietic system denotes a complete paradigm shift of the hierarchical hemopoietic tree. In several studies during the last few years, donor cells have been identified in almost all recipient tissues after allogeneic HSC transplantation (HSCT), supporting the theory that any failing organ could be accessible to regenerative cell therapy. However, the putative potential ability of the stem cells to cross beyond lineage barriers has been questioned by other studies which suggest that hematopoietic cells might fuse with non-hematopoietic cells and mimic the appearance of transdifferentiation. Proof that HSCs have preserved the capacity to transdifferentiate into other cell types remains to be demonstrated. In this review, we focus mainly on clinical studies addressing plasticity in humans who underwent allogeneic HSCT. We summarize the published data on non-hematopoietic chimerism, donor cell contribution to tissue repair, the controversies related to the methods used to detect donor-derived non-hematopoietic cells and the functional impact of this phenomenon in diverse specific target tissues and organs.

Anti-HBs positive occult hepatitis B virus carrier blood infectious in two transfusion recipients

BACKGROUND/AIMS

Occult hepatitis B infection (OBI) in blood donations is not considered infectious when anti-HBs is present.

METHODS

Four months after transfusion of eight blood components during coronary arterial bypass surgery, a 59-year-old patient developed acute hepatitis B. A second 71-year-old patient transfused with a red cell concentrate (RCC) from one of these donations had early HBV infection 7 months post-transfusion. Samples were tested for HBV serological markers and HBV DNA was quantified and sequenced.

RESULTS

One implicated donation contained anti-HBc, anti-HBs (12 IU/L) and 180 IU/ml of HBV DNA. Previous and subsequent samples contained 3-10 times lower viral load and slightly variable anti-HBs. Two previous donations did not cause HBV infection. Recipients of the FFP and RCC from the index donation were both HBV infected and carried genotype D strains with sequences identical to the donor strain.

CONCLUSIONS

Despite anti-HBs, an OBI carrier transmitted HBV to two immunocompetent transfusion recipients.