Transfusion as an Inflammation Hit: Knowns and Unknowns

Abstract

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.

Platelet depletion limits the severity but does not prevent the occurrence of experimental transfusion‐related acute lung injury

“…Platelets possess significant proinflammatory secretory capacity, particularly through the exocytosis of different granules. [18][19][20][21] They express a multitude of receptors that are sensitive to inflammatory danger signals, such as toll-like receptors (TLRs). 22,23 Finally, platelets play an active role in the induction, maintenance, amplification, [24][25][26] and regulation [27][28][29][30] of the inflammatory process by interacting directly with other cells, including neutrophils.…”

“…Platelets possess significant proinflammatory secretory capacity, particularly through the exocytosis of different granules . They express a multitude of receptors that are sensitive to inflammatory danger signals, such as toll‐like receptors (TLRs) .…”

Irradiation and prolonged storage of red cells are associated with increased adverse events

“…can all be attributed to an inflammatory response. Therefore, it has been proposed that all transfusion reactions have an inflammatory component by some authors, and we believe that the different clinical manifestations might represent two spectrums of transfusion‐associated inflammation. The first spectrum is in severity (TRALI vs. FNHTR), and the second is the reaction's localization (local or systemic involvement).…”

“…In contrast, the diagnosis of other acute transfusion reactions, including FNHTR, allergic reactions, transfusion‐associated circulatory overload (TACO), TRALI, hypotensive reactions and transfusion‐associated dyspnoea (TAD), can be subjective and sometimes quite challenging mainly because of a non‐specific clinical presentation and a lack of definitive laboratory findings. Even though there have been proposed mechanisms for these different reactions as summarized in some review articles, an inflammatory component has been considered to exist in these reactions and, as a result, there have been extensive studies on those pro‐inflammatory effectors in recent years. Cytokines in RBC products used to be a major cause of inflammatory reactions as evidenced by the significant reduction of FNHTR after implementation of universal prestorage leucocyte reduction in some countries .…”

Theoretical and experimental ethics: advocacy for blood donors and beneficiaries of blood transfusions

“…There is evidence that transfusing too much, too old, too manipulated or too immunologically incompatible blood etc. can cause clinical inflammation (Garraud et al, ). Inappropriate use of blood, along with overloading, can result in the manifestations of adverse events and complications ( Hendrickson et al, ).…”