THE TUMOR-ASSOCIATED ANTIGEN MAGE-1 IS DETECTABLE IN FORMALIN-FIXED PARAFFIN SECTIONS OF MALIGNANT-MELANOMA

The MAGE-1 gene encodes a protein encompassing a HLA-A1-restricted tar get epitope for cytolytic T lymphocytes, Monoclonal antibodies directe d against the MAGE-1 protein were tested for usage in immunohistology of routine pathology material. Seven formalin-fixed, paraffin-embedded malignant melanomas were studied by the Avidin-Biotin complex (ABC) m ethod with or without different antigen retrieval methods. Native, fro zen tissues from the same tumours were used to validate the results by immunohistochemistry on frozen sections, by PCR for mRNA and by prote in demonstration in tissue extracts using western blotting, Of 4 monoc lonal antibodies tested, mAB 34B and mAB 77B were highly efficient in detecting MAGE-1 protein in deparaffinised sections with the regular A BC method after microwave pretreatment. In a series of an additional 2 8 patients 75% expressed MAGE-1, 50% in a substantial proportion. Foll ow-up studies in 6 patients indicate that the expression pattern remai ns stable but may change substantially within a short range. Immunohis tology is thus a rapid and well-established method that might be used to select and monitor HLA-A1 positive patients with malignant melanoma and other candidate tumours for MAGE-1-directed immuno-therapy.