Term	Definition	Reference
Allergic reactions	Allergic reactions are probably the most frequent, occurring in 1% to 2% of all transfusion reactions. The symptoms range from local or diffuse pruritus, urticaria, erythema and cutaneous flushing to anaphylactic allergic reactions occurring within minutes of the transfusion. Anaphylactoid reactions fall in between the two ends of the spectrum. Uncomplicated allergic reactions are associated with increased histamine (increased during storage), cytokines, mast cell activators (i.e. leukotrienes), and other vasoactive substances (C3a and C5a) produced by donor leukocytes during storage.	Tenorio 2007
Febrile non‐haemolytic transfusion reactions (FNHTR)	FNHTR are defined as a temperature rise of at least 1°C in association with a transfusion or up to 4h after that may be accompanied by chills or rigors. Such reactions are due to acquired antibodies to donor leukocyte antigens or pyrogenic cytokines (IL‐1, IL‐6, IL‐8 and TNF‐D) elaborated by leukocytes present in the blood components or products.	Tenorio 2007
Transfusion‐related acute lung injury (TRALI) (clinical definition)	The earliest definition of TRALI included all patients who developed acute respiratory distress, moderate to severe hypoxaemia (PaO2 30 to 50 mmHg), rapid onset of pulmonary edema, mild to moderate hypotension, and fever (defined as a 18°C to 28°C rise in body temperature from pre‐transfusion baseline) within 6 hours of receiving a plasma‐containing blood transfusion. The definition excluded patients if they had underlying cardiac or respiratory disease.	Goldman 2005; Toy 2005
TRALI (histopathological definition)	As evidenced by interstitial lung leak and lung histology that showed septal thickening, with inflammatory infiltrate consisting mainly of granulocytes was observed in mice transfused with large amounts (4.5 mg/kg) of a murine IgG subclass II.	Looney 2006
Non‐hemolytic febrile transfusion reaction (NHFTR)	Leukocyte apoptosis or monocyte activation, or both, may cause cytokines to accumulate in the blood products during storage. Symptoms/signs: fever, chills.	Heddle 1999; King 2004; Hoffman 2008
Transfusion‐associated graft‐versus‐host disease (TA‐GVHD)	When viable immunological T cells present in blood products are introduced into an immuno‐incompetent host who cannot destroy the donor lymphocytes. Symptoms/signs: nausea, vomiting, anorexia, fever, watery diarrhoea, liver function abnormality, bone marrow aplasia, skin rash, icterus and renal failure.	Hoffman 2008; Rühl 2009