The value of a 51Cr platelet lysis assay as crossmatch test in patients with leukaemia on platelet transfusion therapy.

Current platelet crossmatch testing still results in a significant percentage of false positive or false negative results in oncological patients during platelet support. A 51Cr platelet lysis assay was used for the detection of platelet alloantibodies. We determined the predictive value of this assay as crossmatch procedure on 28 occasions in 14 patients who received random single donor platelet transfusions. To deal with the problem of spontaneous lysis we included a panel of 10 control sera from normal individuals and applied several methods of statistical analysis to these data. It appeared that the use of only one control serum was sufficient when the percentage relative counts was used as the criterion variable, which is of advantage in the practical application of the test. The test values were retrospectively compared with the clinical transfusion response, determined as the 1 h post-transfusion platelet recovery. The 51Cr platelet lysis crossmatch showed false negative results in 1/21 cases and false positive results in 1/7 cases. These data indicate that the 51Cr platelet lysis assay adds a useful dimension to the solution of the problem of selecting compatible platelet donors. Spontaneous lysis of target platelets appeared not to be a problem in the interpretation of test results.