Nonleukoreduced red blood cell transfusion induces a sustained inhibition of neutrophil chemotaxis by stimulating in vivo production of transforming growth factor-beta1 by neutrophils: role of the immunoglobulinlike transcript 1, sFasL, and sHLA-I

An in silico modeling approach to understanding the dynamics of the post-burn immune response

Introduction

Burns are characterized by a massive and prolonged acute inflammation, which persists for up to months after the initial trauma. Due to the complexity of the inflammatory process, Predicting the dynamics of wound healing process can be challenging for burn injuries. The aim of this study was to develop simulation models for the post-burn immune response based on (pre)clinical data.

Methods

The simulation domain was separated into blood and tissue compartments. Each of these compartments contained solutes and cell agents. Solutes comprise pro-inflammatory cytokines, anti-inflammatory cytokines and inflammation triggering factors. The solutes diffuse around the domain based on their concentration profiles. The cells include mast cells, neutrophils, and macrophages, and were modeled as independent agents. The cells are motile and exhibit chemotaxis based on concentrations gradients of the solutes. In addition, the cells secrete various solutes that in turn alter the dynamics and responses of the burn wound system.

Results

We developed an Glazier-Graner-Hogeweg method-based model (GGH) to capture the complexities associated with the dynamics of inflammation after burn injuries, including changes in cell counts and cytokine levels. Through simulations from day 0 - 4 post-burn, we successfully identified key factors influencing the acute inflammatory response, i.e., the initial number of endothelial cells, the chemotaxis threshold, and the level of chemoattractants.

Conclusion

Our findings highlight the pivotal role of the initial endothelial cell count as a key parameter for intensity of inflammation and progression of acute inflammation, 0 - 4 days post-burn.

Human leukocyte immunoglobulin-like receptors in health and disease

Human leukocyte immunoglobulin (Ig)-like receptors (LILR) are a family of 11 innate immunomodulatory receptors, primarily expressed on lymphoid and myeloid cells. LILRs are either activating (LILRA) or inhibitory (LILRB) depending on their associated signalling domains (D). With the exception of the soluble LILRA3, LILRAs mediate immune activation, while LILRB1-5 primarily inhibit immune responses and mediate tolerance. Abnormal expression and function of LILRs is associated with a range of pathologies, including immune insufficiency (infection and malignancy) and overt immune responses (autoimmunity and alloresponses), suggesting LILRs may be excellent candidates for targeted immunotherapies. This review will discuss the biology and clinical relevance of this extensive family of immune receptors and will summarise the recent developments in targeting LILRs in disease settings, such as cancer, with an update on the clinical trials investigating the therapeutic targeting of these receptors.

Low-dose aspirin confers protection against acute cellular allograft rejection after primary liver transplantation

This study investigated the effect of low-dose aspirin in primary adult liver transplantation (LT) on acute cellular rejection (ACR) as well as arterial patency rates. The use of low-dose aspirin after LT is practiced by many transplant centers to minimize the risk of hepatic artery thrombosis (HAT), although solid recommendations do not exist. However, aspirin also possesses potent anti-inflammatory properties and might mitigate inflammatory processes after LT, such as rejection. Therefore, we hypothesized that the use of aspirin after LT has a protective effect against ACR. This is an international, multicenter cohort study of primary adult deceased donor LT. The study included 17 high-volume LT centers and covered the 3-year period from 2013 to 2015 to allow a minimum 5-year follow-up. In this cohort of 2365 patients, prophylactic antiplatelet therapy with low-dose aspirin was administered in 1436 recipients (61%). The 1-year rejection-free survival rate was 89% in the aspirin group versus 82% in the no-aspirin group (hazard ratio [HR], 0.77; 95% confidence interval [CI], 0.63-0.94; p = 0.01). The 1-year primary arterial patency rates were 99% in the aspirin group and 96% in the no-aspirin group with an HR of 0.23 (95% CI, 0.13-0.40; p < 0.001). Low-dose aspirin was associated with a lower risk of ACR and HAT after LT, especially in the first vulnerable year after transplantation. Therefore, low-dose aspirin use after primary LT should be evaluated to protect the liver graft from ACR and to maintain arterial patency.

Transfusion‑related immunomodulation in patients with cancer: Focus on the impact of extracellular vesicles from stored red blood cells (Review)

Red blood cell (RBC) transfusions may have a negative impact on the prognosis of patients with cancer, where transfusion‑related immunomodulation (TRIM) may be a significant contributing factor. A number of components have been indicated to be associated with TRIM. Among these, the impact of extracellular vesicles (EVs) has been garnering increasing attention from researchers. EVs are defined as nano‑scale, cell‑derived vesicles that carry a variety of bioactive molecules, including proteins, nucleic acids and lipids, to mediate cell‑to‑cell communication and exert immunoregulatory functions. RBCs in storage constitutively secrete EVs, which serve an important role in TRIM in patients with cancer receiving a blood transfusion. Therefore, the present review aimed to first summarize the available information on the biogenesis and characterization of EVs. Subsequently, the possible mechanisms of TRIM in patients with cancer and the impact of EVs on TRIM were discussed, aiming to provide an outlook for future studies, specifically for formulating recommendations for managing patients with cancer receiving RBC transfusions.

Intra-Operative Abdominal Drain Placement for Gallbladder Cancer Surgery and Risk of Infectious Complications

Background: Routine intra-operative abdominal drain placement (IADP) is not beneficial for uncomplicated cholecystectomies though outcomes in gallbladder cancer surgery is unclear. This retrospective study hypothesized that patients with IADP (+IADP) for gallbladder cancer surgery have a higher risk of post-operative infectious complications (PIC) compared with patients without IADP (-IADP). Patients and Methods: The 2014-2017 American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database was queried for +IADP and -IADP patients who had gallbladder cancer surgery. Post-operative infectious complications were defined as septic shock, organ/space infection (OSI), or percutaneous drainage. Multivariable analyses were performed to analyze the associated risk of PIC. Results: Of 385 patients, 237 (61.6%) were +IADP. The +IADP patients had higher rates of post-operative bile leak, OSI, re-admission, and increased length of stay (p < 0.05). The +IADP patients were not associated with increased risk of PIC (p > 0.05). Bile leak (odds ratio [OR], 10.61; p < 0.001), peri-operative blood transfusion (OR, 3.77; p = 0.003), biliary reconstruction (OR, 2.88; p = 0.018), and pre-operative biliary stent placement (OR, 3.02; p = 0.018) were the strongest associated risk factors of PIC. Patients with drains in place at or longer than 30 days post-operatively had an increased associated risk compared with patients who did not (OR, 6.88; 95% confidence interval [CI], 2.16-21.86; p < 0.001). Conclusions: More than 60% of gallbladder cancer surgeries included IADP and was not associated with an increased risk of PIC. Intra-operative abdominal drain placement was not associated with an increased risk of PIC, unless drains were left in place for 30 days or longer. Increased risk of PIC was associated with bile leak, peri-operative blood transfusion, pre-operative biliary stent placement, and biliary reconstruction.

Perioperative blood transfusion is associated with an increased risk for post-surgical infection following pancreaticoduodenectomy

BACKGROUND/PURPOSE

Perioperative blood transfusion is common after pancreaticoduodenectomy (PD) and may predispose patients to infectious complications. The purpose of this study is to examine the association between perioperative blood transfusion and the development of post-surgical infection after PD.

METHODS

Patients who underwent PD from 2014 to 2015 were identified in the NSQIP pancreas-specific database. Logistic regression analysis was used to compute adjusted odds ratios (aOR) to identify an independent association between perioperative red blood cell transfusion (within 72 h of surgery) and the development of post-operative infection after 72 h.

RESULTS

A total of 6869 patients underwent PD during this time period. Of these, 1372 (20.0%) patients received a perioperative blood transfusion. Patients receiving transfusion had a higher rate of post-operative infection (34.7% vs 26.5%, p < 0.001). After adjusting for significant covariates, perioperative transfusion was independently associated the subsequent development of any post-operative infection (aOR 1.41 [1.23-1.62], p < 0.001), including pneumonia (aOR 2.01 [1.48-2.74], p < 0.001), sepsis (aOR 1.62 [1.29-2.04], p < 0.001), and septic shock (aOR 1.92 [1.38-2.68], p < 0.001).

CONCLUSION

There is a strong independent association between perioperative blood transfusion and the development of subsequent post-operative infection following PD.

Impact of prestorage leucoreduction of autologous whole blood on length of hospital stay with a subgroup analysis in bilateral hip arthroplasty

BACKGROUND

Although prestorage leucoreduction (LR) of blood components for transfusion has gained favour around the world, evidence of its beneficial clinical effects is ambiguous.

STUDY DESIGN AND METHODS

To reveal whether leucocytes and/or platelets in transfused blood are related to transfusion-related adverse effects, a prospective randomized crossover study was performed on patients who donated autologous blood prior to elective surgery. Among 1487 primary enrolees, a total of 192 patients undergoing two-stage, bilateral total hip arthroplasty were randomized to receive autologous blood that was either prestorage leucoreduced, or not, for the first procedure. For the second procedure, each patient was crossed over to receive alternatively processed autologous blood. Length of hospital stay served as a primary end-point, with perioperative infectious/thrombotic complications, pre- and postoperative laboratory values, and body temperature serving as secondary endpoints.

RESULTS

No significant differences emerged between prestorage LR and non-LR cohorts in length of hospital stay, as well as perioperative infectious/thrombotic complications, postoperative body temperature and duration of fever. Postoperative laboratory values including white blood cell counts and C-reactive protein levels had no significant differences.

CONCLUSION

This study could not prove any superiority of prestorage LR over non-LR for autologous whole blood among patients who underwent total hip arthroplasty.

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.

Red blood cell transfusion in surgical cancer patients: Targets, risks, mechanistic understanding and further therapeutic opportunities

Anemia is present in more than half of cancer patients and appears to be an independent prognostic factor of short- and long-term adverse outcomes. It increases in the advanced period of cancer and perioperatively, in patients with solid tumors who undergo surgery. As a result, allogeneic red blood cell (RBC) transfusion is an indispensable treatment in cancer. However, its safety remains controversial, based on several laboratory and clinical data reporting a linkage with increased risk for cancer recurrence, infection and cancer-related mortality. Immunological, inflammatory and thrombotic reactions mediated by the residual leukocytes and platelets, the stored RBCs per se, the biological response modifiers and the plasticizer of the unit may underlie infection and tumor-promoting effects. Although the causality between transfusion and infection has been established, the effects of transfusion on cancer recurrence remain confusing; this is mainly due to the extreme biological heterogeneity that characterizes RBC donations and cancer context. In fact, the functional interplay between donation-associated factors and recipient characteristics, including tumor biology per se, inflammation, infection, coagulation and immune activation state and competence may synergistically and individually define the clinical impact of each transfusion in any given cancer patient. Our understanding of how the potential risk is mediated is important to make RBC transfusion safer and to pave the way for novel, promising and highly personalized strategies for the treatment of anemia in surgical cancer patients.

Transfusion-related immunomodulation: review of the literature and implications for pediatric critical illness

Transfusion-related immunomodulation (TRIM) in the intensive care unit (ICU) is difficult to define and likely represents a complicated set of physiologic responses to transfusion, including both proinflammatory and immunosuppressive effects. Similarly, the immunologic response to critical illness in both adults and children is highly complex and is characterized by both acute inflammation and acquired immune suppression. How transfusion may contribute to or perpetuate these phenotypes in the ICU is poorly understood, despite the fact that transfusion is common in critically ill patients. Both hyperinflammation and severe immune suppression are associated with poor outcomes from critical illness, underscoring the need to understand potential immunologic consequences of blood product transfusion. In this review we outline the dynamic immunologic response to critical illness, provide clinical evidence in support of immunomodulatory effects of blood product transfusion, review preclinical and translational studies to date of TRIM, and provide insight into future research directions.

Leukocyte Ig-Like Receptors - A Model for MHC Class I Disease Associations

MHC class I (MHC-I) polymorphisms are associated with the outcome of some viral infections and autoimmune diseases. MHC-I proteins present antigenic peptides and are recognized by receptors on natural killer cells and cytotoxic T lymphocytes, thus enabling the immune system to detect self-antigens and eliminate targets lacking self or expressing foreign antigens. Recognition of MHC-I, however, extends beyond receptors on cytotoxic leukocytes. Members of the leukocyte Ig-like receptor (LILR) family are expressed on monocytic cells and can recognize both classical and non-classical MHC-I alleles. Despite their relatively broad specificity when compared to the T cell receptor or killer Ig-like receptors, variations in the strength of LILR binding between different MHC-I alleles have recently been shown to correlate with control of HIV infection. We suggest that LILR recognition may mediate MHC-I disease association in a manner that does not depend on a binary discrimination of self/non-self by cytotoxic cells. Instead, the effects of LILR activity following engagement by MHC-I may represent a “degrees of self” model, whereby strength of binding to different alleles determines the degree of influence exerted by these receptors on immune cell functions. LILRs are expressed by myelomonocytic cells and lymphocytes, extending their influence across antigen-presenting cell subsets including dendritic cells, macrophages, and B cells. They have been identified as important players in the response to infection, inflammatory diseases, and cancer, with recent literature to indicate that MHC-I recognition by these receptors and consequent allelic effects could extend an influence beyond the immune system.

Granulocytes and monocytes apheresis induces upregulation of TGFβ1 in patients with active ulcerative colitis: A possible involvement of soluble HLA-I

Granulocyte and monocyte apheresis has been used in different immune-mediated disorders, mainly inflammatory bowel diseases. The removal of activated leukocytes and several additional immunomodulatory mechanisms have been so far suggested to explain the anti-inflammatory effects of the treatment. Recent data indicate that, during centrifugation based apheresis, sHLA-I adsorbed to plastic circuits is able to induce TGFβ₁ production in activated leukocytes. On these bases, the present study was aimed at analyzing if this model could be applied to a noncentrifugation based apheresis, such as granulocyte and monocyte apheresis. Ten patients with ulcerative colitis were enrolled. Every patient received 5 weekly apheresis treatments. Cellulose acetate beads removed from the column post-GMA were stained by fluorescent anticlass I mAb and examined by fluorescent microscope. Moreover, sFasL plasma concentration, TGFβ₁ plasma levels, and the percentage of TGFβ₁ positive neutrophils were evaluated before and immediately after each single apheresis. Immunofluorescent images revealed a homogeneous layer of a sHLA-I adsorbed to the surface of the beads recovered following the procedure. sFasL plasma concentration progressively increased both following the procedures and during inter-procedure periods. Consistently, also TGFβ₁ plasma levels and the percentage of TGFβ₁ positive neutrophils increased during the procedures with a meaningful relationship with sFasL plasma levels. Taken together, these findings suggest that the immunosuppressive effects attributed to granulocyte and monocyte apheresis might depend, at least in part, on the sensitivity of activated leucocytes to the bioactivity of sHLA-I molecules. J. Clin. Apheresis 32:49-55, 2017. © 2016 Wiley Periodicals, Inc.

Bio-modulators in platelet-rich plasma: a comparison of the amounts in products from healthy donors and patients produced with three different techniques

BACKGROUND

Platelet-rich plasma consists of platelets concentrated in a small volume of plasma and constitutes a reservoir of bio-modulators potentially useful in tissue repair. The amounts of bio-modulators detectable in platelet-rich plasma prepared with various commercial or "in house" methods have been reported, but virtually all the analyses described have been performed on platelet-rich plasma derived from healthy donors. Since leucocyte contamination is technically unavoidable, we investigated whether platelet-rich plasma prepared from patients could contain different amounts of bio-modulators because of a possible activated status of the leucocytes.

MATERIALS AND METHODS

We evaluated platelet-rich plasma prepared with three different techniques (the commercial Vivostat and Biomet recover GPS II systems and an "in house" method) starting from whole blood from healthy donors and patients. Specifically, we compared the levels of sHLA-I, sFasL, platelet-derived growth factor, transforming growth factors-beta and vascular endothelial growth factor in the platelet-rich plasma releasates according to the method of preparation and to the immune system activation status of the subjects.

RESULTS

With the exception of sHLA-I levels, no differences were found in the surrogate indices of lymphocyte activation between healthy donors and patients. No significant differences were found in sHLA-I, sFasL, platelet-derived growth factor, transforming growth factors-beta and vascular endothelial growth factor levels detectable in platelet-rich plasma produced with the three different methods in either healthy donors or patients.

DISCUSSION

On the whole our findings indicate that the overall content of bio-modulators in autologous platelet-rich plasma is not influenced by T-lymphocyte activation status, at least in patients with uncomplicated femoral fractures. The amounts of sFasL and sHLA-I detected in all the platelet-rich plasma releasates studied were very small, far below the amounts detectable in all clinically available blood derivatives and absolutely insufficient to induce sHLA-I and/or sFasL mediated immunomodulation.

Transfusion begets anemia: the effect of aged blood on hematopoiesis

BACKGROUND

Following trauma, transfusion of aged stored blood is often necessary yet associated with increased morbidity and mortality. Despite blood replacement, many patients have a prolonged anemia requiring further transfusions. The effects of aged blood on bone marrow (BM) hematopoiesis have not been studied, and we hypothesized that stored blood suppresses BM function.

METHODS

Blood from Sprague-Dawley rats was stored for 1, 14, or 28 days with the industry preservative citrate-phosphate-dextrose-adenine-1 (CPDA-1). For in vitro studies, 5% supernatant was incubated with normal rat BM and cultured for erythroid (CFU-E) and granulocyte-macrophage (CFU-GM) colony-forming units. Data were compared with cultures of BM alone, 5% control plasma (negative control), and 12% CPDA-1. For in vivo studies, rats were transfused with stored supernatants (5% estimated blood volume (EBV) over 30 minutes). BM from each recipient was cultured for CFU-E and CFU-GM at 3 hours after transfusion. Data were compared with cultures of BM alone. Difference between groups determined by analysis of variance and Tukey's multiple comparison test.

RESULTS

In vitro exposure to CPDA-1, control plasma, or 1-day supernatant (D1) had no effect on BM growth compared with BM alone. In vitro exposure to 14-day (D14) and 28-day (D28) supernatant significantly suppressed CFU-E by 60% and CFU-GM growth by 71% (both p < 0.05) compared with D1 or medial alone. There were no differences between D14 and D28. In vivo exposure to D14 reduced BM CFU-E and CFU-GM growth by 55% (both p < 0.05) compared with D1 supernatant.

CONCLUSION

Plasma from aged blood adversely affects CFU-E and CFU-GM growth in rats. The effect is not mediated by CPDA-1. Transfusion of aged stored blood may contribute to BM dysfunction in critically ill patients, resulting in persistent anemia and the need for further transfusion. This BM dysfunction may also partly explain the observed increased susceptibility to infection.

Blood transfusions with high levels of contaminating soluble HLA-I correlate with levels of soluble CD8 in recipients' plasma; a new control factor in soluble HLA-I-mediated transfusion-modulated immunomodulation?

BACKGROUND

The cause of transfusion-related immunomodulation (TRIM) has proved tantalisingly elusive. An ever-growing body of evidence indicates that the infusion of large amounts of soluble and cell-associated antigens into a recipient can somehow induce TRIM. One soluble molecule that has been implicated in TRIM is soluble human leucocyte antigen I (sHLA-I). However, patients infused with large amounts of sHLA-I do not always and unambiguously experience TRIM. As soluble CD8 (sCD8) molecules have been shown to capable of binding membrane and soluble HLA-I molecules, we focused on sCD8 as a possible modulator of sHLA-I-mediated TRIM.

MATERIAL AND METHODS

To this aim we compared the up-regulation of circulating sCD8 in plasma from patients suffering from the same pathology, but chronically transfused with two different blood derivatives: pre- and post-storage leucodepleted red blood cells which contain low and high levels of contaminating sHLA-I, respectively.

RESULTS

Significantly larger amounts of sCD8 circulating molecules were detectable in the plasma of patients transfused with post-storage leucodepleted red blood cells whose supernatants contained significantly larger amounts of sHLA-I contaminating molecules.

CONCLUSION

With the limitation of indirect evidence, this report introduces a new facet of the bioactivity of sCD8 as a possible modulator of sHLA-I-mediated TRIM.

PRBC-derived plasma induces non-muscle myosin type IIA-mediated neutrophil migration and morphologic change

Context:

Neutrophils are the primary effector cells in the pathogenesis of transfusion-related acute lung injury or multiple organ failure after blood transfusion.

Objective:

We aimed to investigate the effect of fresh (1 day preparation) and aged (42 day preparation) PRBC-derived plasma on neutrophil morphology, migration and phagocytosis.

Materials and methods:

We evaluated the production of reactive oxygen species (ROS) and the expression of non-muscle myosin heavy chain IIA (MYH9) in neutrophils treated with PRBC-derived plasma. We used western blots and antibody arrays to evaluate changes in signal transduction pathways in plasma-treated neutrophils.

Results:

Aged PRBC-derived plasma elicited a stronger oxidative burst in neutrophils when compared with fresh PRBC-derived plasma (p < 0.05). Antibody arrays showed increased phosphorylation of NF-ĸB proteins (p105, p50 and Ikk) in aged PRBC-derived plasma-treated neutrophils. The expression of non-muscle myosin IIA (MYH9), a cytoskeleton protein involved in immune cell migration and morphological change, was also significantly upregulated in neutrophils treated with aged PRBC-derived plasma compared to fresh plasma (p < 0.05). Pretreatment of neutrophils with blebbistatin (a specific type II myosin inhibitor), ascorbic acid (an antioxidant), or staurosporine (a protein tyrosine kinase inhibitor), effectively abrogated the morphological changes, neutrophil migration, and phagocytosis induced by aged PRBC-derived plasma.

Conclusion:

Upregulation of MYH9 in neutrophils treated with aged PRBC-derived plasma and abrogation of neutrophil migration in blebbistatin-treated neutrophils suggested a functional role of MYH9 in the directional migration of immune cells. Our data help elucidate the cellular and molecular mechanisms of transfusion-related injury.

Intravenous immunoglobulin G (IVIG) inhibits IL-1- and TNF-α-dependent, but not chemotactic-factor-stimulated, neutrophil transendothelial migration

High-dose intravenous immunoglobulin (IVIG) has anti-inflammatory effects via incompletely understood mechanisms. By investigating whether IVIG might modulate neutrophil (PMN) recruitment, we observed that IVIG dose-dependently inhibited (by 30-50%) PMN transendothelial migration (TEM) across human umbilical vein endothelial cells (EC) stimulated with IL-1α, IL-1β, TNF-α or IL-1β+TNF-α. Inhibition required the presence of IVIG with the responding PMNs, was attributable to the F(ab)(2) portion and was unrelated to putative contaminants in IVIG. IVIG did not inhibit IL-1β- or TNF-α-induced increase of PMN adhesion to EC, nor did it affect C5a- or IL-8-induced PMN TEM across unstimulated EC. Effects of IVIG and F(ab)(2) fragments were not associated with PMN activation, assessed by CD62L shedding, CD11b upregulation or PMN shape. Thus, IVIG selectively inhibits PMN TEM across inflammatory-cytokine-stimulated - but not unstimulated - EC, perhaps contributing to therapeutic benefit in chronic inflammation with minimal impact on chemotactic-factor-induced PMN recruitment during acute infection.

Down regulation of human natural killer cell-mediated cytolysis induced by blood transfusion: role of transforming growth factor-β(1), soluble Fas ligand, and soluble Class I human leukocyte antigen

BACKGROUND

Human natural killer (NK) cells are thought to play a role in antiviral response and tumor immune surveillance. The molecular mechanisms of down regulation of NK-cell activity observed after red blood cell (RBC) transfusion is still undefined.

STUDY DESIGN AND METHODS

Both effects of blood transfusion (ex vivo) and supernatants (SNs) derived from RBC units unstored (RBC-0) or stored for 5 or 30 days (RBC-5 or -30, respectively) in vitro were analyzed on NK cell-mediated cytolytic activity.

RESULTS

We have found that NK cells isolated from transfused patients on Day 3 lysed the NK-sensitive target cells K562 to a lesser extent than before transfusion. This down regulation of NK-cell activation was evident also for NK-cell killing mediated through the engagement of NK cell-activating receptors as NKG2D, NKp30, NKp46, and CD16. Transfused patients reacquired NK cell-mediated cytolytic activity from Day 5 to Day 7 after transfusion. SN from RBC-30, but not from RBC-0 or RBC-5, strongly inhibited the generation of lymphokine-activated killer (LAK) cells and lysis of the NK-resistant target cell Jurkat in a dose-dependent manner. Transforming growth factor-β1 (TGF-β1) blocking antibodies partially restored the generation of LAK activity. In addition, the depletion of both soluble Class I human leukocyte antigens (sHLA-I) and soluble Fas ligand (sFasL) from SN of RBC-30 completely restored the generation of LAK activity.

CONCLUSIONS

Altogether, these findings would support the idea that blood transfusion-mediated down regulation of NK-cell activity is mediated by sHLA-I, sFasL, and TGF-β1.

Regulation of T-cell immunity by leucocyte immunoglobulin-like receptors: innate immune receptors for self on antigen-presenting cells

Following recognition of microbial patterns, innate immune receptors provide a rapid innate response and trigger antigen-presenting cell maturation to instruct adaptive immune responses. Here we discuss a family of innate immune receptors for self - the leucocyte immunoglobulin-like receptors (LILRs). These LILRs exert powerful inhibitory effects on antigen-presenting cell phenotype and subsequent T-cell responses, and may act to constrain the effects of Toll-like receptor signalling. Despite their broad ligand specificity, differing affinities of LILRs for individual complexes of peptide-major histocompatibility complex can determine the nature of their effect on downstream immune responses. Expression and function of LILRs may be skewed in certain conditions such as cancer or human immunodeficiency virus infection, particularly by ectopic expression of human leucocyte antigen-G, a high-affinity LILR ligand. We discuss the relevance of LILR-mediated immune regulation across a range of scenarios from autoimmunity to transplant medicine, infection and cancer.

Transfusion-related immunomodulation (TRIM): an update

Allogeneic blood transfusion (ABT)-related immunomodulation (TRIM) encompasses the laboratory immune aberrations that occur after ABT and their established or purported clinical effects. TRIM is a real biologic phenomenon resulting in at least one established beneficial clinical effect in humans, but the existence of deleterious clinical TRIM effects has not yet been confirmed. Initially, TRIM encompassed effects attributable to ABT by immunomodulatory mechanisms (e.g., cancer recurrence, postoperative infection, or virus activation). More recently, TRIM has also included effects attributable to ABT by pro-inflammatory mechanisms (e.g., multiple-organ failure or mortality). TRIM effects may be mediated by: (1) allogeneic mononuclear cells; (2) white-blood-cell (WBC)-derived soluble mediators; and/or (3) soluble HLA peptides circulating in allogeneic plasma. This review categorizes the available randomized controlled trials based on the inference(s) that they permit about possible mediator(s) of TRIM, and examines the strength of the evidence available for relying on WBC reduction or autologous transfusion to prevent TRIM effects.