Nodulation of Class I Ano Class II HLA and Melanoma Associated Antigen Expression on Cultured Human Melanoma Cells After in Vitro Administration of K-Mono-Methyl-Triazeno-Benzoate.

Exposition of murine leukemia cells in vivo to 5(3, 3’-dimethyl-l-triazeno) imidazole-4-carboxamide (DTIC), or in vitro to K-mono-methy1-triazeno-benzo ate (MMCOOK), an active metabolite of DTIC which doesn’t need hepatic activation was found to induce a lasting increasing of their immunogenicity. 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 . This did not lead to increased survival of treated mice, since the advantage obtained as regard as malignant cells, i.e. the targets of cell-mediated immunity, was balanced by severe immunodepression of effector lymphocytes. However, in experimental models, where in vivo or in vitro treated leukemic cells were inoculated into healthy syngenic animals, or treated mice were infused with syngenic lymphocytes, reject of leukemia was observed. 9 , 10 , 11 , 12 . In human therapy DTIC is used in the treatment of some malignant neoplasms, such as sarcomas, lymphomas and melanoma, for which it is currently believed to be a drug of choice. A number of observations show that melanoma cells express class I and class II HLA and some tumor associated antigens on their membrane. 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 .