alpha-Fetoprotein and other serum proteins synthesized by endodermal sinus tumor transplanted into nude mice.

The human yolk sac is said to synthesize not only alpha-fetoprotein but also other serum proteins, i.e., albumin, prealbumin, alpha 1-antitrypsin, and transferrin. Two endodermal sinus tumors (yolk sac tumors) were successfully transplanted into athymic nude mice. Concentration of these human serum proteins in the sera of the nude mice and tumor extracts was determined quantitatively by electro-immunodiffusion and radioimmunoassay. alpha-Fetoprotein and albumin were detected in one case, and alpha 1-antitrypsin and alpha-fetoprotein in the other. In the former case, the amount of alpha-fetoprotein synthesized was larger than that of albumin, whereas the amount of alpha-fetoprotein was smaller than that of alpha 1-antitrypsin in the latter. It is tempting to consider that human endodermal sinus tumors simulate the human yolk sac functionally, but the pattern of protein synthesis may differ from case to case.