IMMUNOHISTOLOGICAL LOCALIZATION OF ALPHA-CLASS, MU-CLASS AND PI-CLASSGLUTATHIONE S-TRANSFERASES IN SKIN TUMORS AND CELL-LINES

The indirect immunoperoxidase method was used to demonstrate the prese nce or absence of alpha mu and pi class glutathione S-transferases (GS T) in tissue sections of II malignant melanomas and 15 benign intrader mal naevi. In addition, GST expression was assessed in cultured cell l ines of four secondary malignant melanomas. Pi class GST was always ex pressed in all the malignant melanomas (both tissue sections and cell lines), and in the benign intradermal naevi studied. The alpha and mu class GST were not detected except in two cases where both alpha and m u GST were co-expressed in benign intradermal naevi. it is therefore a pparent that pi class GST was the predominant form expresed in the tum ours and cell lines studied Electron microscopy was undertaken to exam ine the intracellular and extracellular distribution of GST using both indirect immunoperoxidase staining with an unlabelled pi GST antibody , as well as a gold-labelled GST pi antibody. Pi class GST was found t o be present on the sur face of intact cells as well as around the mit ochondria and in nuclear spaces in the melanoma cell line studied.