***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND Febrile , nonhemolytic transfusion reactions are the most frequent adverse reactions to platelets . A number of observations argue against the widely held view that these reactions result from the interaction between antileukocyte antibodies in the recipient and leukocytes in the platelet product . We sought to determine whether substances in the plasma or the cells in the product cause reactions to transfused platelets . METHODS We separated st and ard platelet concentrates  into their plasma and cellular components and then transfused both portions in r and om order . Patients were monitored for reactions during all transfusions . Before each transfusion , the concentration of cytokines ( interleukin-1 beta and interleukin-6 ) was measured in the platelet products . Studies were also performed on the platelet products to determine the effect of storage on the concentration of cytokines . RESULTS Sixty-four pairs of platelet-product components ( the plasma supernatant and the cells ) were administered to 12 patients . There were 20 reactions to the plasma supernatant and 6 reactions to the cells ( chi-square = 6.50 , P = 0.009 ) . Eight transfusions were associated with reactions to both products . The plasma component was more likely to cause severe reactions than the cells ( chi-square = 9.6 , P < 0.01 ) . A strong positive correlation was observed between the reactions and the concentration of interleukin-1 beta and interleukin-6 in the plasma supernatant ( P < 0.001 and P = 0.034 , respectively ) . In vitro studies demonstrated that interleukin-1 beta and interleukin-6 concentrations rise progressively in stored platelets and that these concentrations are related to the leukocyte count in the platelet product . CONCLUSIONS Bioreactive substances in the plasma supernatant of the platelet product cause most febrile reactions associated with platelet transfusions . Removing the plasma supernatant before transfusion can minimize or prevent these reactions A variety of patient and product-related factors influenced the outcome of 6379 transfusions given to 533 patients in the Trial to Reduce Alloimmunization to Platelets ( TRAP ) . Responses measured were platelet increments , interval between platelet transfusions , and platelet refractoriness . Patient factors that improved platelet responses were splenectomy and increasing patient age . In contrast , at least 2 prior pregnancies , male gender , splenomegaly , bleeding , fever , infection , disseminated intravascular coagulation , increasing height and weight , lymphocytotoxic antibody positivity , an increasing number of platelet transfusions , or receiving heparin or amphotericin were associated with decreased posttransfusion platelet responses . Platelet factors that were associated with improved platelet responses were giving ABO-compatible platelets , platelets stored for 48 hours or less , and giving large doses of platelets while ultraviolet B ( UV-B ) or gamma irradiation decreased platelet responses . However , in alloimmunized lymphocytoxic antibody-positive patients , the immediate increment to UV-B-irradiated platelets was well maintained , whereas all other products showed substantial reductions . Refractoriness to platelet transfusions developed in 27 % of the patients . Platelet refractoriness was associated with lymphocytotoxic antibody positivity , heparin administration , fever , bleeding , increasing number of platelet transfusions , increasing weight , at least 2 pregnancies , and male gender . The only factors that reduced platelet refractoriness rates were increasing the dose of platelets transfused or transfusing filtered apheresis platelets We prospect ively r and omized 51 patients with haematological malignancy requiring platelet concentrates ( PCs ) to receive either single donor platelet-pheresis products ( SD-PC ) , PCs made from pooled buffy coats ( BC-PC ) or pooled units of platelets made by the platelet-rich plasma method ( PRP-PC ) . The leucocyte content of each type of PC was 0.33 ( 0.03 - 13.5 ) , 5.68 ( 0.19 - 99.0 ) and 365 ( 65 - 910 ) x 10(6 ) ; median ( range ) , respectively ; P < 0.0001 . All red cell transfusions were leucodepleted by filtration . Statistical comparison of the probability of the occurrence of a nonhaemolytic febrile transfusion reaction ( NHFTR ) following transfusion of PCs in patients in each group showed a significant decrease for the SD-PC and BC-PC groups ( 0.031 and 0.038 , respectively ) when compared with PRP-PC ( 0.171 ) ; P = 0.0001 . The actual corrected platelet count increments ( CCI ) at 1 - 6 and 18 - 24 h post-transfusion for all three types of PC did not differ significantly . We conclude that transfusion of PRP-PC is associated with a significant increase in NHFTR A r and omized study was performed in 54 thrombocytopenic patients with acute leukemia . Alloimmunization of recipients of r and om multiple-donor platelet concentrates ( MD group ) was compared to that of patients receiving r and om single-donor platelets ( SD group ) . In the SD patients , formation of alloantibodies ( mostly anti-HLA ) occurred less frequently ( p less than 0.002 ) , after a longer time period ( p less than 0.002 ) , and after a higher number of transfusions ( p less than 0.005 ) as compared to MD patients . SD patients also became refractory to r and om platelets less frequently ( p less than 0.005 ) , after a longer time period , and after a higher number of transfusions ( p less than 0.02 ) . In SD patients , the increments after the first and the last transfusion were in the same range , whereas in MD patients , the 1-hr ( p less than 0.001 ) and the 24-hr ( p less than 0.025 ) increments decreased from the first to the last transfusion . Thus , the use of r and om SD platelet transfusions postponed alloimmunization Thrombocyte substitution is an essential prerequisite for intensive cytoreductive therapy in acute leukemia . Evaluating  228 thrombocyte transfusions in 17 patients shows that the clinical effectiveness of thrombocyte concentrates  can be increased by making the coordination of HLA antigens of donor and receiver as good as possible . When measured in the corrected increment ( CI ) 24 hours after transfusion , the effectiveness of  A3/B1 match preparations  ( CI = 7.0 + /- 1.6 ) is significantly higher than that of r and om preparations ( CI = 3.0 + /- 0.5 ) . With the presence of HLA antibodies an effective substitution ( CI24 greater than or equal to 4.5 ) can only be achieved by A3/B1 match thrombocytes . This can only be realized by applying the fourfold thrombapheresis of single donors It is generally assumed that febrile nonhemolytic transfusion reactions are an immunologically mediated reaction involving the recipient 's plasma and the white cells in the donor unit . This has led to the use of white cell reduction and pretransfusion medication , to try to minimize these reactions . To better underst and febrile transfusion reactions , a prospect i ve study was performed in which all patients receiving platelet and red cell transfusions in a tertiary-care medical center were interviewed before and after transfusion to obtain information about the typical presentation of the syndrome . It was found that transfusion reactions were much more frequently associated with platelet transfusion ( 30.8 % ) than with red cell transfusion ( 6.8 % , p < 0.0005 ) . The routine use of antipyretics prevented most episodes of fever but did not prevent the occurrence of other symptoms such as chills , cold , and discomfort . The application of logistic regression analysis revealed that the dominant factor determining the risk of a reaction was not white cell contamination , but the age of the component ( p < 0.005 ) . The significant relationship between reaction and the increasing age of the component suggests that cytokines released in the component during storage may be responsible for many reactions to blood components BACKGROUND Prophylactic platelet transfusions are usually administered to patients receiving myelotoxic chemotherapy when their platelet count falls below 20,000 per cubic millimeter . Some observations suggest that lower platelet counts can be appropriate in patients in stable condition , but the safety of lower thresholds is uncertain . METHODS We evaluated 255 adolescents and adults ( age , 16 to 70 years ) with newly diagnosed acute myeloid leukemia ( but not acute promyelocytic leukemia ) , who were treated in 21 centers . One hundred thirty-five patients were r and omly assigned to receive a transfusion  when their platelet count fell below 10,000 per cubic millimeter ( or 10,000 to 20,000 per cubic millimeter in those with a temperature above 38 degrees C , with active bleeding , or a need for invasive procedures ) , and 120 patients were assigned to receive a transfusion when their platelet count was less than 20,000 per cubic millimeter . RESULTS Patients in the group with a threshold of 10,000 platelets per cubic millimeter received 21.5 percent fewer  platelet transfusions than the patients in the group with a threshold of 20,000 platelets per cubic millimeter ( P=0.001 ) . The numbers of red-cell units transfused were not significantly different between groups . Major bleeding ( defined as any bleeding more than petechiae or mucosal or retinal bleeding ) occurred in 21.5 and 20 percent of patients , respectively ( P=0.41 ) , and on 3.1 and 2.0 percent of the days of hospitalization . One episode of fatal cerebral hemorrhage occurred in the group with a threshold of 10,000 platelets per cubic millimeter ; none occurred in the other group ( P= 0.95 ) . Actuarial estimates of survival during induction chemotherapy , actuarial estimates of the absence of major bleeding , and the length of hospital stay were not significantly different in the two groups . CONCLUSIONS The risk of major bleeding during induction chemotherapy in adolescents and adults with acute myeloid leukemia ( except acute promyelocytic leukemia , which we did not study ) was similar with platelet-transfusion thresholds of 20,000 per cubic millimeter and 10,000 per cubic millimeter ( or 10,000 to 20,000 per cubic millimeter when body temperature exceeded 38 degrees C , there was active bleeding , or invasive procedures were needed ) . Use of the lower threshold reduced platelet use by 21.5 percent BACKGROUND Methods of platelet preparation may alter the recovery and survival characteristics of platelets following transfusion . As suggested by a recent clinical trial , platelet recovery may be better preserved with apheresis platelet preparations than with platelets prepared from whole blood by the platelet-rich plasma ( PRP ) method . STUDY DESIGN AND METHODS In vivo platelet recovery and survival of autologous leukoreduced ( LR ) apheresis platelets and autologous filter-LR PRP platelets were compared in 22 healthy volunteers using a paired crossover design . On the same day , each participant gave one apheresis platelet donation and one whole blood donation from which platelets were recovered from the PRP . The sequence of donations was r and omly assigned for each participant . Following 5 days of storage and bacterial screening , a sample from each platelet product was labeled with either (51)chromium or (111)indium ( r and omly assigned ) and both sample s were simultaneously re-infused into the original donor . Recovery and gamma-function platelet survival were calculated for each platelet product using the multiple hit mathematical model . RESULTS Five day stored LR-apheresis platelets had 18.8 percent better recovery , and 32.9 percent longer gamma-survival than filter-LR PRP platelets . Stored apheresis platelets had lower p-selectin expression and higher morphology scores than stored PRP platelets . CONCLUSIONS Filter-LR PRP platelet preparation appears to adversely affect platelet recovery and survival characteristics . The reasons for this effect are not clear . These results may not apply to all apheresis and PRP methods of platelet preparation Abstract R and om-donor platelet concentrates ( PC ) prepared from pooled buffy coats have recently been described as an alternative method for platelet preparation . We evaluated such PCs in the clinical setting compared with a st and ard PC from platelet apheresis . PCs were prepared either from pools of buffy coats ( BC-PC ) or from single donors ( SD-PC ) with the cell separator CS-3000 plus . PCs were stored for up to 5 days before transfusion . We compared fresh PC ( day 1 ) with stored ( day 2–3 ) and long-stored PC ( day 4–5 ) . For analysis , platelet increment in the recipient was determined immediately and 16–22 h ( mean 20 h ) after transfusion , corrected for total body area and transfused platelets ( CCI ) . A total of 316 PCs were administered to 36 thrombocytopenic patients suffering from various hematological disorders . Patients with detectable HLA or platelet-specific antibodies or splenomegaly were excluded from the study . Mean platelet content of the PC was 262 × 109 for BC-PC and 251 × 109 for SD-PC . The 20-h CCI after transfusion of fresh PC was slightly higher with BC-PC than 
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No conclusions could be made for the outcomes of alloimmunization and refractoriness .
CONCLUSIONS Owing to the small number of trials and lack of comparability of PLT products for leukoreduction , we were unable to draw definitive conclusions about the clinical benefits of APCs compared with WBD PLTs .