cted because 18- to 24-hour increments were inadequate in response to fresh, random 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.20:T544,In this prospective study, 26 consecutive patients being treated for haematological malignancies receiving standard (i.e. non-leucocyte-depleted) blood components were observed for the development of refractoriness to platelet transfusions. One hundred and sixteen of the 266 (44%) platelet transfusions failed to produce a satisfactory response. In 102/116 (88%), the poor response was in the presence of non-immune factors known to be associated with platelet refractoriness. Non-immune factors were present alone in 78/116 (67%), and in combination with immune factors in a further 24/116 (21%). Immune factors (HLA and platelet-specific antibodies) were present during 29/116 (25%) of unsuccessful platelet transfusions. Statistical analysis confirmed that platelet refractoriness was significantly associated with the presence of non-immune factors. The non-immune factors associated with refractoriness were often multiple, most frequently a combination of fever, infection and antibiotic therapy. This study provides evidence that immune mechanisms were not the predominant cause of platelet refractoriness in the patient population studied. It also suggests that measures for the prevention of HLA alloimmunisation, such as leucocyte depletion, may have a limited impact in reducing the incidence of refractoriness to platelet transfusions.21:T509,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, random donor platelets. A corrected count increment (CI) (CI=[posttransfusion count—pretransfusion count]×body surface area [sq m]/platelets transfused×10¹¹) at one hour of 10×10³/μL or greater was associated with absence of lymphocytotoxic antibody, whereas increments of less than 10×10³/μL were generally associated with high levels of strongly cytotoxic antibody. HLA-matched transfusions produced no improvement in increments when the previous one-hour CI had been 10×10³/μL 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. (JAMA243:435-438, 1980)

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Abstract

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