My laboratory is interested in the cellular and molecular mechanisms that allow the fetus to escape rejection by the maternal immune system during pregnancy. We have been focusing on two non-mutually exclusive possibilities. The first possibility is that there is an attenuation of the afferent arm of the immune response with regards to the fetal allograft. This might involve altered dendritic cell behavior at the maternal/fetal interface leading to the defective priming of maternal T cells, or the tolerization of T cells by antigens directly released hematogenously from the conceptus. The second possibility is that there is a defect in the efferent arm of the immune response, namely that alloreactive maternal T cells are unable to home to the maternal/fetal interface or perform effector functions there despite their activation. It is likely that a deeper understanding of these issues will have implications for peripheral immune tolerance and autoimmunity, tumor immunology, leukocyte trafficking, and clinical disorders of pregnancy.