Svetlana Cherepanoff, Enisa Hasic, Mark C Gillies

Purpose:
To describe S100 expression in the retinalpigment epithelium (RPE) of normal human eyes andin eyes with both tumour and non-tumour pathology.

Methods:
S100 immunohistochemistry was per-formed using polyclonal rabbit anti-human S100antibody and the Bond Polymer Red Detection kitfrom Leica with the Leica Bond II automatedimmunohistochemistry protocol. A total of 14 humaneyes were included in the study. RPE S100 expressionwas examined in six normal control eyes, two evis-cerations, two pthisical eyes, one enucleationfor retinoblastoma, one enucleation for choroidalmelanoma and two enucleations for chronic retinal detachment.

Results:
RPE in normal control eyes showed patchyweak cytoplasmic S100 staining. S100 was morestongly expressed in both the cytoplasm and nucleus ofall pathological eyes, except in retinoblastoma. Expres-sion was not uniform. Eyes with long term retinaldetachment showed the strongest nuclear and cyto-plasmic S100 staining.

Conclusions:
S100 may be a novel marker of RPEabnormality, particularly in eyes with long term retinaldetachment.