Immunoregulatory activity of cells from lymph nodes draining the uterus of allopregnant mice.

The presence of a local immunosuppressive environment in the vicinity of the developing fetus has been suggested to explain survival of the semi-allogeneic fetus in a potentially hostile maternal immunologic environment. The presence of nonspecific suppressor cells in the uterus of pregnant mice has been well-documented. It has been suggested that the local immunosuppressive environment extends to the lymph nodes draining the uterus of pregnant mice. Studies undertaken to investigate this hypothesis have provided conflicting data. The current study was performed as an attempt to resolve some of the controversial results obtained from previous studies and to characterize more extensively the nature of lymph node suppressor cells. Our results clearly demonstrated that neither specific nor non-specific immunosuppression was expressed within lymph nodes draining the uterus of allopregnant mice. Cells obtained from draining lymph nodes consistently exhibited a normal capacity to respond to alloantigens whether by proliferation or through cytotoxic T lymphocyte (CTL) generation. We conclude that immunosuppression fails to develop in draining lymph nodes during pregnancy and therefore plays little or no role in controlling the development of antifetal immune responses.