Partial characterization of uterine cells responsible for suppression of murine maternal anti-fetal immune responses.

Several studies have demonstrated that uterine cells are capable of suppressing in vitro immune responses in a nonspecific manner. Two types of cells have been implicated as responsible for suppression, cells with the features of macrophages and a small lymphocyte-like cell. In the present study the maternal anti-paternal mixed lymphocyte reaction was used to investigate further the characteristics of uterine suppressor cells. Three distinct suppressor cell populations were identified: highly suppressive macrophages, small lymphocyte-like cells, and a morphologically heterogeneous third population of highly suppressive cells. The data from this study suggest that pregnant murine uteri contain a variety of cells capable of discouraging lymphocyte proliferation in vitro.