Tissue eosinophil count on whole slide image
As an alternative method for histopathological assessment of samples,
glass slides were prepared for whole slide image (WSI) acquisition using
previously described methods.19 The slides were
digitalised (Ventana DP 200, Roche, Basel, Switzerland). Component TIF
image tiles from each slide were then imported into the open source
digital pathology software QuPath version 0.2.3.20 In
order to more precisely quantify tissue eosinophils, two
0.1mm2 fields in sub-epithelial layers in each
H&E-stained tissue section with high eosinophil density were selected
on QuPath. Areas of crush were not selected. Crush areas were defined as
abnormally elongated dark thinned nuclei in stroma.21Eosinophils were independently counted on H&E-stained tissue sections
by the first author (SW) and a senior anatomical pathology registrar
(SL) in a blinded manner. Eosinophils in the epithelium and
intravascular space were excluded.
The eosinophil cell count for each of the two reviewers was calculated
as the average number of eosinophil cells across the two
0.1mm2 areas and was expressed as eosinophils per
0.1mm2. The final eosinophil cell count was calculated
as the mean of the two reviewers’ scores.