NEWLY ESTABLISHED MST-1 TUMOR-CELL LINE AND TUMOR-INFILTRATING LYMPHOCYTE CULTURE FROM A PATIENT WITH SOFT-TISSUE MELANOMA (CLEAR-CELL SARCOMA) AND THEIR POTENTIAL APPLICATIONS TO PATIENT IMMUNOTHERAPY

The establishment and characterisation of paired autologous tumour cel l, line (MST-1) and tumour-infiltrating lymphocyte (TIL) culture from a tumour mass of a 14-year-old Taiwanese girl with soft tissue melanom a are described. MST-1 cells grown in vitro were heterogeneous in morp hology, ranging from floating round cells, loosely attached round/oval or elongated cells with prominent pseudopod-like processes, to well-a ttached spindle and elongated dendritic cells without obvious pseudopo ds. Immunostaining revealed that major melanoma-associated antigens, s uch as S100 protein, HMB-45, melanotransferrin, chondroitin sulphate p roteoglycan, and the gangliosides GD2 and GD3, were consistently expre ssed by the tumour tissue, severe combined immunodeficiency (SCID) mou se xenograft and derived cell lines. Flow cytometric analysis of the t umour DNA content showed an index of 1.8 relative to normal peripheral blood lymphocyte DNA. Chromosome analysis revealed all cells at a hyp otetraploid level with several clonal chromosome aberrations, includin g deletions at 10p and 12q, an addition at 12q, translocations t(1;14) and t(5;6). Electron microscopy showed melanosome structures. This ob servation and the expression of the major melanoma-associated antigens were all indicative of the melanocytic origin of MST-1 tumour. Interl eukin-2 (IL-2) expanded TILs had the predominant CD8(+) phenotype and the capacity to lyse cells of the cultured autologous tumour. The avai lability of the soft tissue melanoma cell line, the SCID mouse xenogra ft tumour system as well as autologous TILs described herein would pro vide useful materials for identifying T-cell-defined antigens as well as a model system for devising individualised cancer biotherapeutic st rategies. This cell line can also be used for further studies aimed at uncovering the histogenesis of this rare cancer.