Human embryonal carcinoma cells and their differentiation in culture.

Based on the study of two clonal cell lines, 2102Ep and TERA-2, isolated from human germ cell tumours, we have identified several properties that are commonly expressed by human embryonal carcinoma (EC) cells, the stem cells of teratocarcinomas. These properties include the expression of surface antigens SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81, and the presence of cytokeratin in the cytoplasm. However, some human EC cells lack expression of SSEA-3 and -4, although glycolipids containing these epitopes can be extracted from such variant cells. Analysis of the glycolipid composition of TERA-2 cells suggests that the switching of oligosaccharide core structure synthesis from globo-series to lacto- and ganglio-series is a key event during the differentiation of these cells. Variant, SSEA-3 and -4-negative EC cells may have already initiated these changes while retaining other features of the EC phenotype. Other studies have indicated that human EC cells variably express class I MHC antigens. We have shown that interferon induces expression of these surface molecules in EC cells without inhibiting their growth or inducing their differentiation or resistance to viral infection.