[Studies on the interaction between trophoblastic invasion and maternal immune cell infiltration at the implantation site in early human pregnancy by means of double immunoperoxidase technic using monoclonal antibodies].

Interaction between trophoblastic invasion and maternal immune cell infiltration at the implantation sites in early human pregnancy was analyzed by means of a double immunoperoxidase technique using Troma-1, a rat monoclonal antibody, which recognizes trophoblastic cells and a set of mouse monoclonal antibodies to react with various immune cells. The results were as follows. The most prominent immune cells in the implantation sites were monocytes/macrophages, which were positive for HLA-DR. These cells were adjacent to trophoblastic cells which were infiltrating into the decidua basalis. It therefore appeared that these cells function as "antigen presenting cells" which recognize and present the processed fetal information to maternal T cells. A small number of cells with mature T cell markers were found to be infiltrating around the anchoring villi and the extra-villous trophoblastic cells in the decidua compacta. But a larger number of T cells were adjacent to the villi in the decidua spongiosa and the extra-villous trophoblastic cells invading the decidua spongiosa and the myometrium. These cells may therefore play a role in preventing trophoblastic cells from invading the myometrium in the implantation sites. A relatively large number of cells with E rosette receptors but without mature T cell markers were observed in the decidua basalis, but few were found in the myometrium, into which a larger number of mature T cells were infiltrating. The distribution of particular cells was similar to that of endometrial granulocytes studied in our laboratory. There were thus likely to be immune cells in humans equivalent to non-T granulated suppressor cells in mice, which have been shown to suppress the generation of cytotoxic T cells (Clark et al.).