Incorporation of alpha-1-antichymotrypsin into carcinoma cell nuclei of human stomach adenocarcinoma transplanted into nude mice.

Human stomach adenocarcinomas containing alpha-1-antichymotrypsin (ACT) in their cell nuclei were transplanted into nude mice. The presence of ACT was monitored using an immunohistochemical technique with horseradish peroxidase-labeled rabbit anti-ACT Fab' as well as single radial immunodiffusion. Two weeks after transplantation, ACT could be found neither in transplanted carcinoma cells nor in the sera of carcinoma-bearing nude mice. However, if human ACT was injected i.v., it could be detected in the transplanted carcinoma cell nuclei 2 h after injection. The ACT was detected immunohistochemically and was confirmed by biochemical fractionation using 125I-labeled ACT. On the other hand, the amount of ACT production was not sufficient to indicate biosynthesis. These results demonstrated that ACT detected in stomach carcinoma cell nuclei was not synthesized in carcinoma cells but was incorporated from the blood circulation.