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patient samples), DAT and elution of antibodies from the patient’s red cells for identification. Treatment of DHTRs is usually supportive, sometimes requiring further transfusion. The offending antibodies must be recorded on the transfusion laboratory computer and medical records and patients are usually issued with an ‘Antibody Card’ to carry and present to clinical staff whenever further transfusion is required. Patients investigated by Blood Services reference laboratories will also have their antibodies recorded on a central database. All DHTRs should be reported to SHOT and the MHRA. 5.2.4.2: Transfusion-associated graft-versus-host disease (TA-GvHD) This rare and almost always fatal complication occurs when viable lymphocytes in a blood donation engraft in the patient and mount an immune response against the recipient’s cells of a different HLA type. At-risk patients usually have impaired cell-mediated immunity and are unable to reject the foreign cells. These include fetuses receiving intrauterine transfusion, patients with inherited immunodeficiency disorders affecting T-cell function, medical procedures causing very severe immunosuppression such as allogeneic stem cell transplantation or treatment with specific chemotherapy drugs such as purine analogues. TAGvHD has occasionally been reported in non-immunosuppressed patients receiving a blood transfusion from an HLA-matched donor or a close relative with HLA types in common. Patients receiving conventional combination chemotherapy for cancer are not at increased risk of TA-GvHD and it has not been reported in HIV positive transfusion recipients. Clinical aspects of TA-GvHD prevention in haemato-oncology patients and neonates/infants are discussed in Chapters 8 and 10 respectively. Symptoms classically occur 7 to 14 days (maximum 30 days) after transfusion with fever, skin rash, diarrhoea, disturbed liver function and worsening bone marrow aplasia. Diagnosis is based on showing the typical features of acute GvHD in biopsies of affected organs and demonstration of donor-derived cells or DNA in the patient’s blood or tissues. The UK Blood Services provide specialist diagnostic services. Only one case of TA-GvHD has been reported in the UK since 2000 (an intrauterine transfusion of non-irradiated maternal blood). Routine leucodepletion of blood components has clearly reduced the risk of TA-GvHD but it remains essential to ensure that all at-risk patients receive irradiated red cells or platelet components. The BCSH Guidelines on the Use of Irradiated Blood Components (http://www.bcshguidelines.com) regularly update the list of patients and therapeutic agents that require the use of irradiated blood components in the light of current research. 5.2.4.3: Post-transfusion purpura (PTP) Affected individuals develop a very low platelet count and bleeding 5 to 12 days after transfusion of red cells. The typical patient is a parous female who is negative for a common platelet antigen, most commonly HPA-1a, and may have been initially sensitised by carrying a HPA-1a positive fetus in pregnancy. PTP is caused by re-stimulation of platelet-specific alloantibodies in the patient that also damage their own (antigen-negative) platelets by an ‘innocent bystander’ reaction. This severe, and potentially fatal, complication has become rare since the introduction of leucodepleted blood components. Advice in diagnosis and management should be sought from transfusion medicine specialists and Blood Service laboratories. Platelet transfusions are usually ineffective (but may be given in high doses in patients with life-threatening bleeding) but most patients show a prompt and sustained response to high-dose intravenous immunoglobulin (IVIg). 5.3: Infectious hazards of transfusion Transfusion Handbook / 5: Adverse effects of transfusion page 13 of 17 Historically, transfusion-transmitted infections (TTIs) dominated the transfusion safety agenda but they are now rare in developed countries. However, constant vigilance is required to counter the risk from established and newly emergent pathogens in the era of mass international travel. Novel transfusiontransmissible agents, such as prions, have also emerged to threaten the safety of the blood supply. 5.3.1: Viral infections With modern donor selection and testing, hepatitis B, hepatitis C and HIV transmission are now very rare in the UK

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