Immunohistochemical staining for S-lOO and GFAP proteins of spontaneous brain tumours in Wistar rats
The occurrence of spontaneous brain tumours in rats is relatively rare. The need for a histological correct classiﬁcation of rat brain tumours is of great importance in evaluation of chemical induced brain neoplasms in long term carcinogenicity studies.
The value of additional immunohistochemical staining for GFAP and S-100 proteins were investigated in a long term carcinogenicity study. Astrocytomas were positive for the GFAP protein but no tumours had a clear positive reaction for the S-100 protein. The most common tumour type was granular cell tumour which did not stain for the GFAP and S-100 proteins. However one tumour of this type had a subpopulation of cells that stained for GFAP protein. In the light of the relatively few astrocytomas in the material, no ﬁrm conclusion on the value of staining for GFAP protein can be drawn. However the investigation suggests that staining for GFAP protein is of value in the diagnosis ofastrocytomas. Staining for S-100 protein did not show a positive reaction in any ofthe tumours. In conclusion staining for S-100 protein in this study did not have any diagnostic value.