Antibodies to neutrophil and HLA antigens can cause pulmonary transfusion reactions and in some cases acute lung injury. not known. In conclusion, patients and donors involved with pulmonary transfusion reactions can be quickly typed for HLA antigens and tested for HLA antibodies but testing for neutrophil antibodies and antigens requires the use of a reference laboratory. Leukocyte antigens were described more than 50 years ago using leukocyte agglutination assays. Classic leukoagglutinins included antibodies to HLA antigens and neutrophil specific antigens. The HLA antigens, a family of closely related molecules located in the same region of chromosome 6, have been studied extensively and have been found play a critical role in almost all aspects of cellular and humoral immunity. Antibodies to HLA antigens can cause acute rejection of transplanted organs, refractoriness to platelet transfusions, and transfusion reactions. Neutrophil-specific antigens are known as Human Neutrophil Antigens (HNA). HNA antigens are made up of Dinaciclib several unrelated molecules expressed predominantly if not exclusively by neutrophils. HNA antigens are a diverse group of molecules with widely different functions. Neutrophil antibodies cause neonatal alloimmune neutropenia, autoimmune neutropenia of childhood, and transfusion reactions including TRALI. While the HLA and HNA antigen systems are quite different, these two antigen systems are associated by transfusion reactions. Antibodies to both antigen systems can cause both febrile and pulmonary transfusion reactions. The identification of HLA and neutrophil antigens and antibodies to these antigens are important for the evaluation of patients and donors involved in pulmonary transfusion reactions. The methods currently used to type HLA and neutrophil antigens and screen for HLA and HNA antibodies as well as strategies to evaluate patients and donors implicated in transfusion reactions are reviewed. TYPES OF TRANSFUSION REACTIONS CAUSED BY LEUKOCYTE ANTIBODIES Antibodies to neutrophil and HLA antigens can cause Dinaciclib a variety of transfusion reactions. These include febrile transfusion reactions, pulmonary transfusion reactions in recipients of granulocyte concentrates as well as recipients of plasma made up of blood components. Febrile DLEU7 Transfusion Reactions In the 1950s Brittingham found that the transfusion of whole blood into Dinaciclib patients with leukoagglutinins could cause febrile reactions.1 Both HLA and neutrophil-specific antibodies cause these reactions. Brittingham found that these reactions could be prevented by removing the buffy-coats from the whole blood1. The risks of such reactions can now be significantly reduced in frequency and severity by transfusing leukocyte-reduced RBC and platelet components.2C4 Pulmonary Transfusion Reactions Granulocyte transfusion recipients sometimes experience transfusion reactions characterized by shortness of breath, fever, and hemoglobin oxygen desaturation.5C7 Chest x-rays in patients experiencing these reactions may uncover new or worsening pulmonary infiltrates, but the pulmonary dysfunction is usually mild to moderate in severity and resolves within a few hours. These reactions occur in granulocyte transfusion recipients alloimmunized to HLA class I or neutrophil-specific antigens. Most often they are caused by antibodies to HLA antibodies.5C7 These reactions are likely a result of antibody-antigen interactions that cause the transfused Dinaciclib granulocytes to become trapped in the pulmonary capillaries causing ventilation/perfusion mismatching and hypoxia. Plasma Made up of Blood Products can also cause pulmonary transfusion reactions. In 1957 Britthingham found that the transfusion Dinaciclib of leukoagglutinins sometimes caused severe pulmonary transfusion reactions.1 The transfusion of 50 mL of plasma with strong leukocyte agglutinins resulted in immediate faintness followed in about 45 minutes by vomiting, diarrhea, chills, fever, severe hypotension, severe tachypnea, dyspnea, cyanosis, and initial leukopenia followed by leukocytosis. The following day the transfusion recipient.