What does QBC stand for?

Fluorecens microscopy was for a long time too expensive but. "In 1991, however, the development of a relatively cheap, interference-filter system (a multi-layered excitation filter combined with a barrier filter) designed for use with AO in a standard light microscope provided a low-cost tool for malaria diagnosis employing AO (Kawamoto, 1991 b). A combination of centrifugation, AO staining and fluorescence microscopy was developed into the quantitative buffy coat (QBC) method.