CD63 and cystic fibrosis: In this study [19, 23], the authors co-measure surface levels of CD203c and CD63 on peripheral blood basophils following in vitro stimulation with A. fumigatus allergen/extract (see Fig 3B) and test whether increases Median Fluorescence Intensity (MFI) for each marker distinguish CF-ABPA from CF patients (clinical status was confirmed by conventional clinical diagnostic techniques).