Background: The sensitivity of flow cytometric measurement of platelet antibodies in a crossmatch technique was investigated.
Study design and methods: The corrected count increment after platelet transfusion was compared with the fluorescence ratio determined by flow cytometric measurement.
Results: When crossmatching was performed before transfusion(s) in alloimmunized patients, a fluorescence ratio < or = 1.7 was associated with satisfactory responses (corrected count increment > or = 7.5), and the predictive values for negative and positive crossmatch results were 94 and 87 percent, respectively. Analysis of antigen preservation during platelet storage with antibodies to HLA alpha-chain, HLA-B27, HPA-1a, and HPA-3a showed that platelets can be stored, refrigerated, for up to 4 weeks without significant loss of HLA class I and HPA-1a. There was a slight but continuous loss of HPA-3a upon storage.
Conclusion: Flow cytometric measurement of fluorescence in the platelet suspension immunofluorescence test can be used for platelet crossmatching, with sensitivity and predictive values comparable to those of previously described techniques and with the advantage of automation.