Interpretation of the Obtained Test and Control Data

Comment. Several techniques can be used to assess activation of washed platelets (Fig. 1). The actual method of detection of platelet activation is probably less important than the technique of platelet preparation itself, including the selection of suitable platelet donors.

A positive test result is one in which heparin-dependent platelet activation occurs at therapeutic concentrations of heparin (0.1-0.3 U/mL) but is inhibited at very high (100 U/mL) heparin concentrations and in the presence of platelet Fc receptor-blocking monoclonal antibody. By assessing activation in the presence of different LMWH compounds or danaparoid, studies of in vitro cross-reactivity can be performed (discussed subsequently). It is important to ensure that control HIT sera, including one or more weak positive controls, react as expected. Given the experience from a workshop on testing for HIT antibodies (Eichler et al., 1999), we recommend exchange of weak positive control sera among laboratories for quality control.

0 0

Post a comment