A PUTATIVE MARKER FOR HUMAN-MELANOMA - A MONOCLONAL-ANTIBODY DERIVED FROM THE MELANOMA GENE IN THE XIPHOPHORUS MELANOMA MODEL

A MoAb was raised against a peptide corresponding to an exposed domain of the putative tyrosine kinase receptor protein encoded by Xmrk, a g ene involved in melanoma formation and/or progression in the Xiphophor us fish melanoma model. The antibody reacts specifically with cells fr om human melanocytic lesions, ie, common acquired nevi, primary and me tastatic melanoma biopsies. No reactivity with other cells, including normal melanocytes, was observed in the biopsies or with cells in biop sies from normal tissue (skin, liver, lung, spleen) and from other mal ignancies including those of neuroectodermal origin. The reactivity wa s very weak and variable in metastatic melanomas but very strong and c haracteristic of a receptor-type antigen in primary melanomas, a stage in melanoma progression in which cells have acquired metastasizing po tential. It is suggested that the antigen recognized may be involved i n growth promotion and represents the human equivalent of the fish mel anoma gene product.