Oksanen K, Kekomaki R, Ruutu T, Koskimies S, Myllyla G. in the magnitude of class I HLA antibodies, and UV treatment resulted in a significant 3-fold reduction in the magnitude of class II HLA antibodies. Both treatments resulted in shorter persistence of class I HLA antibodies. CONCLUSIONS These data demonstrate that leukoreduction and LCZ696 (Valsartan) UV treatment of blood products results not only in a reduction in the incidence of HLA antibody production, but also in lower and more transient HLA antibody levels among sensitized transfusion recipients. strong class=”kwd-title” Keywords: Alloimmunization, HLA Antibodies, Leukoreduction, UV treatment Intro Blood transfusion is one of the most common sources of allogeneic exposure, and recipients of blood products are exposed to numerous alloantigens indicated on the surface of donor WBCs, RBCs, and platelets. Many blood recipients become alloimmunized to human being leukocyte antigens (HLA) on WBC and platelets, which can LCZ696 (Valsartan) limit subsequent transfusion of these cellular products. Following transfusion of reddish cell products, individuals can generate an alloresponse against RBC and/or WBC antigens. Anti-RBC reactions can cause dangerous hemolytic transfusion reactions, so attempts are made to match major reddish cell antigens between donor and recipient to prevent their development. These attempts are effective and rates of RBC alloimmunization IL4 are fairly low, although some highly transfused patient populations (such as sickle cell and thalassemia individuals) are at increased risk of developing RBC antibodies (Abs).1-7 In contrast, alloimmunization against WBC antigens (predominantly HLA) is definitely common following transfusion of reddish cells due to contaminating WBCs and because pre-transfusion HLA matching isn’t just impractical, but has been associated with graft versus host disease.8-11 Following receipt of platelet transfusions, the alloimmune response is focused on antigens expressed on WBCs and platelets, including class We HLA and additional platelet antigens. Antibody reactions against these antigens can be highly problematic, resulting in refractoriness to LCZ696 (Valsartan) subsequent platelet transfusions.12,13 Interestingly, the magnitude of the HLA Ab response appears to be important in determining if immune mediated refractoriness will occur, as low-to-moderate level Abs do not predict platelet transfusion failure.14 Rates of antibody generation against HLA antigens following transfusion are high, ranging from 7-64%, depending on study, patient populations, and quantity and type of transfusions.12,15-23 Previously pregnant women and previously transfused individuals have been shown to have a higher frequency of HLA antibody production when LCZ696 (Valsartan) subsequently transfused.19,21,22,24 HLA Abs can usually be recognized within a fortnight after exposure and while sometimes only short-lived, can persist for long periods in some recipients.15,16,22,25-27 Historically, HLA Abs have been detected by lymphocytotoxicity assays (LCA), which detect higher level, match fixing antibodies.23,28,29 In comparison, newer and more sensitive multianalyte bead-based assays additionally detect low to moderate level antibodies, as well as non-complement fixing Abs and those directed against a potentially broader range of HLA antigens.30-33 The introduction of leukoreduction offers been shown in most studies to reduce however, not eliminate the frequency of alloimmunization,15,17-20,23,34 having a less obvious impact on previously pregnant recipients. 35 Leukoreduction reduces the number of WBCs from approximately 5108 cells/unit to less than 5106 cells/unit, and generally less than 1106 cells/unit with current methods. The observed reductions in rates of alloimmunization most likely reflect this decreased dose of antigen. The use of UV treated products, while less extensively studied, offers similarly been shown to reduce the rates of alloimmunization.23 UV treatment is a component of some LCZ696 (Valsartan) commercially available pathogen reduction methods used clinically in Europe in the treatment of platelets and plasma components. While alloimmunization appears to be less frequent when products are exposed to UV light, interpretation of published studies has been complicated, as individuals receiving.