***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: Summary . Refractoriness to r and om‐donor platelets as a result of alloimmunization remains a major problem in long‐term platelet transfusion therapy despite the use of HLA‐matched platelets . We have therefore studied the use of two methods for detection of platelet associated IgG as platelet crossmatch tests for the selection of platelet donors . These methods use radiolabelled staphylococcal protein A ( 125I‐SPA ) and peroxidase anti‐peroxidase ( PAP ) , respectively Seventy-nine  platelet transfusions to 73 thrombocytopenic patients with cancer were analyzed to determine whether a platelet count obtained one hour after transfusion could help differentiate between alloimmunization and other clinical factors that result in rapid platelet destruction . These transfusions were selected because 18- to 24-hour increments were inadequate in response to fresh , r and om donor platelets . A corrected count increment ( Cl ) ( Cl=[posttransfusion count-pretransfusion count]Xbody surface area [ sq m]/platelets transfusedX10 ' ' ) at one hour of 10X103/microliter or greater was associated with absence of lymphocytotoxic antibody , whereas increments of less than 10X103/microliter were generally associated with high levels of strongly cytotoxic antibody .  HLA-matched transfusions produced no improvement in increments when the previous one-hour Cl had been 10X103/microliter or greater , whereas in the other group significantly better increments were obtained . A one-hour posttransfusion count is a simple test that correlates well with the presence of antibody against HLA antigens , is valuable in predicting the need for HLA-matched platelets , and helps avoid wasteful , empirical use of such transfusions A latex agglutination assay was evaluated for the purpose of identifying compatible platelet donors for alloimmunized recipients .  Assay reagents were prepared by adsorbing detergent-solubilized , donor-specific platelets to polystyrene latex beads . Semiquantitative results for up to 30 donors can be completed in less than 1 hour . These reagents retained their immunoreactivity for at least 3.5 months . A retrospective study has established the assay 's upper limit of compatibility . The prospect i ve study evaluated transfusions to a group of multiply transfused patients . Part I evaluated 143 crossmatched , single-donor platelet transfusions given to 50 patients . In 96 percent of the cases , a positive crossmatch was associated with an unsuccessful transfusion outcome ; in 84 percent of the transfusions , a negative crossmatch predicted a satisfactory platelet increment . The overall predictability , sensitivity , and specificity were 87 , 62 , and 99 percent , respectively . Part II evaluated 105 transfusions given to the 43 patients ( of 50 ) in whom no incidence of fever , sepsis , or bleeding could be documented . A positive crossmatch was 96-percent efficient in predicting an unsuccessful transfusion , whereas a negative crossmatch was associated with an adequate platelet increment following 89 percent of the transfusions . The overall predictability was 91 percent , the sensitivity was 72 percent , and the specificity was 99 percent . Within-run and between-run variations were 6.3 and 6.2 percent , respectively . These results demonstrate that detergent-solubilized platelet antigens , immobilized on latex particles , can be used in a cost-effective crossmatching procedure Although the value of HLA matching for the selection of platelet donors for patients refractory to r and om platelets is beyond doubt , even perfectly matched combinations sometimes fail to give a satisfactory transfusion response . With HLA typing and negative lymphocytotoxicity crossmatches , 35 % of the  platelet transfusions administered to 15 patients gave disappointing results ( 29 of 82 ) . Additional crossmatching with the newly developed platelet fluorescence test described in this paper reduced the unexpected transfusion failures to 7 % ( 6 of 82 ) . Five of these failures were observed in one patient . The target of the antibodies detected with this platelet fluorescence test is not yet fully specified . It seems probable that both HLA and platelet-specific non-HLA antibodies were detected . No correlation of the results of platelet transfusions  with the presence or absence of leukoagglutinating antibodies was found 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 R and omized controlled trials have shown a reduction in platelet alloimmunization and refractoriness in patients with acute leukemia ( AL ) with the use of poststorage leukoreduction of blood products . Universal prestorage leukoreduction ( ULR ) of red cell and platelet products has been performed in Canada since August 1999 . We conducted a retrospective analysis of 13 902 platelet transfusions in 617 patients undergoing chemotherapy ( CT ) for AL or stem cell transplantation ( SCT ) before ( n = 315 ) and after ( n = 302 ) the introduction of ULR .  Alloimmunization was significantly reduced ( 19 % to 7 % , P < .001 ) in the post-ULR group . Alloimmune platelet refractoriness was similarly reduced ( 14 % to 4 % , P < .001 ) . Fewer patients in the post-ULR group received HLA-matched platelets ( 14 % vs 5 % , P < .001 ) . Alloimmunization and alloimmune refractoriness in the 318 patients who were previously pregnant and /or transfused were also reduced after ULR ( P = .023 and P = .005 , respectively ) . In a Cox regression model , the 3 independent factors that predicted for alloimmune refractoriness were nonleukoreduced blood products ( relative risk [ RR ] , 2.2 [ 95 % CI , 1.2 - 4.3 ] ) , a history of pregnancy and /or transfusion ( RR , 2.3 [ 95 % CI , 1.3 - 4.2 ] ) , and receipt of 13 or more platelet transfusions ( RR , 6.0 [ 95 % CI , 2.4 - 15.3 ] ) . In conclusion , ULR reduces alloimmunization , refractoriness , and requirements for HLA-matched platelets when applied as routine transfusion practice to patients receiving CT or SCT Four platelet compatibility assays were performed on serum and platelet or lymphocyte sample s from 38 closely HLA-matched donor/recipient pairs involved in 55 single-donor platelet transfusions . The 22 patients studied were refractory to transfusions of pooled r and om-donor platelets . Of the four assays ( platelet suspension immunofluorescence , PSIFT ; 51Cr release ; microlymphocytotoxicity ; and a monoclonal anti-IgG assay , MAIA ) , the MAIA was most predictive of platelet transfusion outcome ( predictability , 74 % for one-hour posttransfusion platelet recovery and 76 % for 24-hour recovery ) . The only other assay to reach statistical significance was the PSIFT ( 63 % predictability for one-hour posttransfusion recovery ) . The degree of HLA compatibility between donor and recipient ( exact matches v those utilizing cross-reactive associations ) was unrelated to the ability of the MAIA to predict transfusion results . The MAIA may be capable of differentiating HLA antibodies , ABO antibodies , and platelet-specific antibodies responsible for failure of HLA-matched and selectively mismatched single-donor platelet transfusions BACKGROUND HLA-matched platelets and crossmatch-compatible platelets are used to support thrombocytopenic patients who are refractory to r and omly selected platelets . Data supporting the effectiveness of crossmatch-compatible platelets are limited , being essentially restricted to the subset of refractory patients previously shown to be alloimmunized . The authors ' hospital does not test for alloimmunization . To determine the effectiveness of crossmatch-compatible platelets in an unselected group of refractory patients , the use of such platelets for all patients who are refractory to r and om-donor platelets  was review ed . STUDY DESIGN AND METHODS All patients who received crossmatch-compatible platelets between January 1991 and May 1994 were retrospectively review ed . All study patients were refractory to r and om-donor platelets  , having two consecutive corrected count increments ( CCIs ) of < 10,000 . A solid-phase red cell adherence method was used for platelet crossmatching , and CCI was used to monitor the effectiveness of each platelet transfusion . RESULTS A total of 475 crossmatch-compatible platelet components were administered to 66 evaluable patients who were refractory to r and om-donor platelets .  A significant improvement was found in the mean CCI when crossmatch-compatible platelets were compared with r and omly selected platelets ( p < 0.0001 ) : an increase of 8000 + /- 6100 ( mean + /- SD ) . In 59 percent ( 39/ 66 ) of the patients , the mean CCI improved to at least 7,500 and in 41 percent ( 27/66 ) to at least 10,000 . If the 10 patients for whom crossmatch-compatible platelets were not identified are included , the mean CCI in 51 percent ( 37/76 ) of the refractory patients improved to at least 7,500 ; in 36 percent ( 27/76 ) , it improved to at least 10,000 . The effectiveness of crossmatch-compatible platelets  did not decline with continued use . CONCLUSION Crossmatch-compatible platelet components significantly improve the mean CCI for approximately one-half of patients who are refractory to r and om-donor platelets , even when the patients are not preselected for having alloimmunization to explain their refractory state BACKGROUND The use of crossmatch-compatible platelets ( PLTs ) improves posttransfusion corrected count increments ( CCIs ) in patients with alloimmune PLT refractoriness . However , few reports address the efficacy of utilizing this strategy for patients requiring intensive PLT transfusion therapy lasting several weeks to months . STUDY DESIGN AND METHODS Medical records of patients with two or more PLT crossmatch assays performed between 2002 and 2010 were review ed . All patients were refractory to r and om single-donor apheresis PLT units  , defined as two consecutive 1-hour posttransfusion CCIs of less than 7500 . A commercial solid-phase adherence assay was used for crossmatching . RESULTS Seventy-one patients were included . A median of four crossmatch assays were performed per patient ( range , 2 - 17 ) . Mean percent reactivity in initial ( 58.6 % ) versus last ( 55.3 % ) crossmatch assay for each patient demonstrated no trend toward progressive alloimmunization ( p = NS ) . A total of 738 crossmatched PLT units were administered with a mean ± st and ard deviation CCI of 7000 ± 7900 ( n = 443 units with adequate 1-hr posttransfusion counts ) , a significant improvement over r and om PLTs ( p < 0.001 ) . Patients with an initial crossmatch reactivity of greater than 66 % were significantly more likely to demonstrate at least one panreactive crossmatch assay , impacting the availability of compatible PLTs for optimum transfusion support . One patient ( 1.4 % ) developed WHO Grade IV bleeding . CONCLUSIONS Progressive alloimmunization to mismatched antigens does not impact medium-term transfusion support with crossmatched PLTs . Increased reactivity in the initial crossmatch assay can serve as a trigger to initiate workup for HLA-matched PLTs as a second-line approach . However , for most patients , medium-term transfusion support with crossmatched PLTs offers an effective and rapid first-line approach to management of PLT transfusion refractoriness Despite the use of HLA-matched platelets for alloimmunized recipients , transfusion failures occur . In order to reduce these failures , we investigated the use of a radi 
    Output:
    
No trend was observed regarding relative utility of the various commonly employed techniques .
Cross-matched PLTs are useful in increasing PLT counts in alloimmunized , transfusion-refractory HT patients , but data about their impact on hemorrhage and mortality are lacking