Immunohistochemical localization of ganglioside GD3 in human malignant melanoma, epithelial tumors, and normal tissues

The specific tissue distribution of melanoma-associated ganglioside II3-alpha-N-acetylneuraminosyl-alpha 2---8-N-acetylneuraminosyllactosylceramide (GD3) was studied on 175 cryopreserved, unfixed human tissue sections with R-24 mouse monoclonal antibody by indirect immunoperoxidase staining. A striking specificity of monoclonal antibody R-24 for malignant melanoma tissues was established. Ganglioside GD3 was detected in all 21 tissue sections of 21 patients with primary melanoma and in all 37 probes of 24 patients with metastatic malignant melanoma. The majority of tumor cells in the samples of primary malignant melanoma expressed GD3; however, GD3 expression was more heterogeneous in samples of metastatic lesions even in different metastases of the same patient. Of 11 nevi, 9 reacted with monoclonal antibody R-24, while melanocytes in the basal layer of normal skin stained only weakly and irregularly. None of the 32 normal and 12 fetal human tissue types were R-24 positive, but a strong cytoplasmic staining was observed with single cells in the dermis and in the interstitial tissue of the gastrointestinal tract, in the interlobular septa of the thymus, and in other distinct locations. Only two malignant carcinoid tumors of 38 nonmelanomatous tumors tested reacted with monoclonal antibody R-24.