Evaluation of HLA-DR typing by ethidium bromide fluorescence

Sixty individuals were typed for D-related human leukocyte antigens (HLA-DR) using two methods: the standard eosin exclusion method and a recently described one-color ethidium bromide technique. As a result, 88 of the 90 DR antigens detected by the standard technique were also detected by one-color fluorescence (sensitivity = 97.8 percent). However, of the 99 DR antigens identified by ethidium bromide fluorescence, 11 were left undetected by eosin exclusion (sensitivity = 88.9 percent). The one-color ethidium bromide fluorescence technique, although originally intended to conserve technical time, demonstrated an additional advantage in our laboratory. The enhanced sensitivity of the procedure may help in the identification of previously undetected DR antigens.