Platelet and TRALI: From blood component to organism.

Even though used systematically with leukocyte reduction, platelet transfusions still cause adverse reactions in recipients. They include Transfusion-Related Acute Lung Injury (TRALI), respiratory distress that occurs within six hours of the transfusion. The pathophysiology of this transfusion complication brings complex cellular communication into play. The role, particularly inflammatory, played by blood platelets in TRALI pathophysiology has been demonstrated, but is still under debate. Blood platelets play a role in inflammation, particularly via the CD40/CD40L (sCD40L) immunomodulator complex. In this study, we examine in particular the specific involvement of the CD40/CD40L (sCD40L) complex in the inflammatory pathogenesis of TRALI. This molecular complex could be a major target in a TRALI prevention strategy. Improving the conditions in which the platelet concentrates (PC) are prepared and stored would contribute to controlling partly the risks of non-immune TRALI.

Transfusion-associated hazards: A revisit of their presentation.

As a therapy or a support to other therapies, despite being largely beneficial to patients in general, transfusion it is not devoid of some risks. In a moderate number of cases, patients may manifest adverse reactions, otherwise referred to as transfusion-associated hazards (TAHs). The latest French 2016 haemovigilance report indicates that 93% of TAHs are minor (grade 1), 5.5% are moderate (grade 2) and 1.6% are severe (grade 3), with only five deaths (grade 4) being attributed to transfusion with relative certainty (imputability of level [or grade] 1 to 3). Health-care providers need to be well aware of the benefits and potential risks (to best evaluate and discuss the benefit-risk ratio), how to prevent TAHs, the overall costs and the availability of alternative therapeutic options. In high-income countries, most blood establishments (BEs) and hospital blood banks (HBBs) have developed tools for reporting and analysing at least severe transfusion reactions. With nearly two decades of haemovigilance, transfusion reaction databases should be quite informative, though there are four main caveats that prevent it from being fully efficient: (ai) reporting is mainly declarative and is thus barely exhaustive even in countries where it is mandatory by law; (aii) it is often difficult to differentiate between the different complications related to transfusion, diseases, comorbidities and other types of therapies in patients suffering from debilitating conditions; (aiii) there is a lack of consistency in the definitions used to describe and report some transfusion reactions, their severity and their likelihood of being related to transfusion; and (aiv) it is difficult to assess the imputability of a particular BC given to a patient who has previously received many BCs over a relatively short period of time. When compiling all available information published so far, it appears that TAHs can be analysed using different approaches: (bi) their pathophysiological nature; (bii) their severity; (biii) the onset scheme; (biv) a quality assessment (preventable or non-preventable); (bv) their impact on ongoing therapy. Moreover, TAHs can be reported either in a non-integrative or in an integrative way; in the latter case, presentation may also differ when issued by a blood establishment or a treating ward. At some point, a recapitulative document would be useful to gain a better understanding of TAHs in order to decrease their occurrence and severity and allow decision makers to determine action plans: this is what this review attempts to make. This review attempts to merge the different aspects, with a focus on the hospital side, i.e., how the most frequent TAHs can be avoided or mitigated.

Determination of predictors of severity for recipient adverse reactions during platelet product transfusions.

The introduction of allogeneic cells is not a natural process, even if the transfusion is therapeutic and - when no alternative exists, as is often the case - essential. Transfusion of cellular products creates some level of danger sensed by recipients. Danger may manifest itself clinically or biologically, in which case we are dealing with recipient adverse reactions. Platelet concentrate transfusion in particular may be responsible for notable adverse reactions. Some appear to be inevitable, while others are tied to recipient factors: either health or genetic characteristics. The authors' research is specifically focused on platelet storage lesion and stress factors, and the means of controlling them to ensure greater recipient tolerance.

Transfusion as an Inflammation Hit: Knowns and Unknowns.

Transfusion of blood cell components is frequent in the therapeutic arsenal; it is globally safe or even very safe. At present, residual clinical manifestations are principally inflammatory in nature. If some rare clinical hazards manifest as acute inflammation symptoms of various origin, most of them linked with conflicting and undesirable biological material accompanying the therapeutic component (infectious pathogen, pathogenic antibody, unwanted antigen, or allergen), the general feature is subtler and less visible, and essentially consists of alloimmunization or febrile non-hemolytic transfusion reaction. The present essay aims to present updates in hematology and immunology that help understand how, when, and why subclinical inflammation underlies alloimmunization and circumstances characteristic of red blood cells and - even more frequently - platelets that contribute inflammatory mediators. Modern transfusion medicine makes sustained efforts to limit such inflammatory hazards; efforts can be successful only if one has a clear view of each element's role.