[Immunohistochemical study on trophoblast subpopulations in normal pregnancy and trophoblastic disease]

Trophoblast subpopulations were analyzed by their antigen expressions in normal pregnancy and trophoblastic disease. Samples were taken from uteri which were removed surgically. Frozen sections were stained by an avidin-biotin-peroxidase complex method, using monoclonal antibodies to HLA antigens and anti-Trop 1 antibody. Troma 1, a rat monoclonal antibody, was used for the identification of trophoblasts. The results were as follows: Troma 1 reacted with all trophoblasts specifically and could be used as a trophoblast marker in sections. HLA-A,B,C was negative on syncytiotrophoblast and villous cytotrophoblast but positive on nonvillous cytotrophoblast in normal pregnancy and hydatidiform mole. Some choriocarcinoma cells were positive for HLA-A,B,C and they were intermediate to large cytotrophoblast-like cells. No trophoblasts were positive for HLA-DR. Trop 1 was positive on villous cytotrophoblast in normal pregnancy and hydatidiform mole. Some choriocarcinoma cells were positive for Trop 1 and they were exclusively negative for HLA-A,B,C. From these immunohistochemical findings, trophoblasts of normal pregnancy and hydatidiform mole were divided into syncytiotrophoblast, villous cytotrophoblast, and nonvillous cytotrophoblast. Choriocarcinoma cells were classified into syncytiotrophoblast-like cells and three kinds of cytotrophoblast-like cells. They were analogous to those of normal pregnancy and hydatidiform mole to some extent, but a choriocarcinoma-specific subpopulation which was negative for HLA-A,B,C, HLA-DR, and Trop 1 was recognized.