Natural killer and natural cytotoxic cells are present at the maternal-fetal interface during murine pregnancy.

NK cell activity has been detected in the early murine decidua, and hypothesized to be mediated by granulated metrial gland (GMG) cells. The possibility that natural cytotoxic (NC) cells are also present in the decidua has not been investigated. In this study mAb to NK cells (anti-NK-1.1) and NC cells (anti-NC-1.1) were used to characterize the decidual cells of days 8-14 pregnant (CBA x C57BL/6) F1 mice. Flow cytometric and immunohistological analyses showed predominantly NK-1.1+ and NC-1.1+ large and granular single nucleated decidual cells with abundant cytoplasm. A 'bright' and a 'dim' subset were identified for both NK-1.1+ and NC-1.1+ cells. The NC-1.1dim and NK-1.1dim cells increased in number and size as pregnancy progressed. When tested in 51Cr-release assays, the decidual cells showed significant levels of both NK and NC activities which increased with progression of pregnancy. The NK and NC activities were partially inhibited (47 and 34%) by preincubation of the decidual cells with anti-NC-1.1 and complement (C'), or anti-NC-1.1 alone. Results indicate that natural cell-mediated cytotoxicity in the decidua is in part, at least, mediated by NK-1.1+ and NC-1.1+ cells, and that the NK-1.1dim and NC-1.1dim cells are very likely to be GMG cells. This is the first report of NC cells in the mouse uterus.