Alpha1-antitrypsin and alpha-fetoprotein. Protein markers in endodermal sinus (yolk sac) tumors

A combined immunocytochemical and quantitative serum and tissue study was performed on a group of endodermal sinus (yolk sac) tumors, localizing and measuring both alpha1-antitrypsin (AAT) and alpha-fetoprotein (AFP) in tumor tissue and patient sera. Utilizing indirect immunofluorescent and triple-sandwich immunoperoxidase methods, both proteins were demonstrated within intra- and extracellular periodic acid-Schiff-positive hyaline globules characteristic of the tumor, as well as within the cytoplasm of tumor epithelial cells lining endodermal sinuses, where AAT deposition predominated. Tumor tissue extracts confirmed the presence of significant quantities of both proteins, and pretreatment serum elevations of both showed a parallel decline during therapy. In this study, AAT is characterized as a tumor protein marker for the first time, and a parallelism between AAT and AFP is demonstrated in both serum and tumor tissue. These findings represent additional supportive evidence for the yolk sac origin of endodermal sinus tumors in man.