A human
immature teratoma cell line was established from
tumor tissue of the ovary. The cell line, designated YK , synthesized and secreted
alpha-fetoprotein, but there was a gradual decrease in the synthesis of this
protein during serial passage. The doubling time at passage 43 was about 20.3 hr, and the plating efficiency was 30 to 40%. Tumorigenicity of the cell line in athymic nude mice was 100% even when 10(4) cells were inoculated s.c. When the cell line was cultivated for 5 days in the presence of 80 microM
retinoic acid, proliferation was completely inhibited, while
alpha-fetoprotein secretion into the medium was increased. Specific
lactate dehydrogenase activity in the
tumor grown in nude mice as well as in the cultured cells was 8 times higher than that in the original
tumor. The activity of
alpha-hydroxybutyrate dehydrogenase in the original
tumor was similar to that in the
tumor grown in nude mice, while the activity in the cultured cells was about 2.5 times higher than those in both original
tumor and the
tumor grown in nude mice. The original
tumor had all five ordinary bands of
lactate dehydrogenase isoenzymes. In contrast, both the cultured cells and the
tumor grown in nude mice had a characteristic band which was considered to have similar electrophoretic mobility as testicular
lactate dehydrogenase X isoenzyme in humans.