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 hy pothesized 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 (ant i-NK-1.1) and NC cells (anti-NC-1.1) were used to characterize the dec idual cells of days 8-14 pregnant (CBA x C57BL/6) F1 mice. Flow cytome tric and immunohistological analyses showed predominantly NK-1.1(+) an d NC-1.1(+) large and granular single nucleated decidual cells with ab undant cytoplasm. A 'bright' and a 'dim' subset were identified for bo th NK-1.1(+) and NC-1.1(+) cells. The NC-1.1(dim) and NK-1.1(dim) cell s increased in number and size as pregnancy progressed. When tested in Cr-51-release assays, the decidual cells showed significant levels of both NK and NC activities which increased with progression of pregnan cy. 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-1.1(dim) and NC-1.1(dim) cells are very likely to be GMG cells. This is the first report of NC cells in the mouse uterus.