Human melanoma cell lines: an immunofluorescence and ultrastructural study

Two human melanoma cell lines (OAL-1 and OAIy-2) were obtained from primary tumors. Electron microscopy and indirect immunofluorescence for S-100 protein and human melanoma associated antigen p97a were used to characterize the cell lines. Ultrastructural correlation between primary tumor cells and cultured cells was investigated. The ultrastructural features of OAL-2 cells were similar to those of primary tumor cells. However, OAL-1 cells showed a fibroblast-like appearance, quite different from that of the primary tumor cells. This fibroblast-like appearance persisted after 50 subcultures of the OAL-2 cell line and suggests cellular dedifferentiation. No spontaneous re-differentiation of the cells to the original phenotype of the primary tumor cells was observed even after 50 subcultures.