Exosomes from red blood cell units bind to monocytes and induce proinflammatory cytokines, boosting T-cell responses in vitro

Abstract

• Exosomes in blood are proinflammatory and may contribute to transfusionrelated immune modulation.• Exosomes act via antigenpresenting cells to potentiate T-cell survival and mitogeninduced proliferation.Extracellular vesicles (EVs) are small, double membrane vesicles derived from leukocytes, platelets, and cells of other tissues under physiological or pathological conditions. Generation of EVs in stored blood is thought to be associated with adverse effects and potentially immunosuppression in blood transfusion recipients. We measured the quantity and cells of origin for EVs isolated from stored red blood cell (RBC) units and tested whether they had any effects on T-cell-mediated immune responses. Mixing peripheral blood mononuclear cells (PBMCs) with EVs resulted in secretion of proinflammatory cytokines and chemokines and increased survival of unstimulated PBMCs. EVs augmented mitogen-induced CD4 1 and CD8 1 T-cell proliferation in an antigenpresenting cell (APC)-dependent manner. We demonstrated that EVs interacted primarily with monocytes and induced proinflammatory cytokine secretion. We also showed that the exosome fraction of EVs and not larger microvesicles was responsible for induction of TNF-a production by monocytes. Furthermore, blockade of CD40 or CD40L accessory molecules largely neutralized the EV augmentation of T-cell responses, implying a role for cell-cell interaction between T cells and EV-activated monocytes. Contrary to our hypothesis, the data demonstrate that EVs isolated from RBC units increase the potency of APCs and boost mitogen-driven T-cell proliferative responses. (Blood. 2014;123(5):687-696)

Platelet and red blood cell interactions and their role in rheumatoid arthritis

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Does RBC Storage Age Effect Inflammation, Immune Function and Susceptibility to Transfusion Associated Microchimerism in Critically Ill Patients? Adverse Effects of RBC Storage in Critically Ill Patients

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