Flow cytometry: a tool in immunohematology for D+W (Du) antigen evaluation?

We performed a flow-cytometric analysis of the expression of D antigen in D+W samples (previously termed Du). We also analysed a series of D-positive and D-negative (cde phenotype) samples to obtain positive and negative controls, respectively. The evaluation was carried out by immunofluorescence and the intensity of positivity was expressed as mean channel value (MCV) of fluorescence. Results demonstrated that D+W samples have lower expression (less than 1 log) than D-positive cases (p > 0.001, Student t test), while cde samples show the same MCVs as negative controls. Moreover, it was also possible to set a grading of D antigen expression and to analyze cases difficult to assess by agglutination only.