New Actors for the Immunological Mechanisms Involved in the Materno- Fetal Tolerance

Tolerance to the semi-allogeneic fetal graft by the maternal immune system is the consequence of a wide panel of mechanisms that may be interconnected. In the present work we discuss the participation of new actors that might contribute to the materno-fetal tolerance and their involvement in the failure of a successful pregnancy occurring in patients with recurrent spontaneous abortions (RSA). The presence of blocking factors (BF) of the maternal allogeneic response in the sera of fertile women is usually associated with a successful pregnancy. In this context, Galectin-1 (a β- galactoside-binding protein expressed at sites of T-cell activation and immune privilege) and RANTES (regulated on activated normal T cells, expressed and secreted) are able to immunosuppress the allogeneic response. This effect induces a significant increase of the apoptosis of CD45R0+ cells and is accompanied by caspases activation and Bcl-2 down regulation. Moreover, trying to identify reliable markers for RSA diagnosis, we investigated some activation markers like CD69 (an early activation marker), SLAM (signaling lymphocytic activation molecule) and the pattern of Th1/Th2 cytokine expression in the preimplantation endometrium and in the peripheral blood from fertile and RSA women. Finally, as a treatment for RSA patients, we evaluated the effectiveness of the alloimmunization, with paternal leukocyte and investigated the immunomodulation induced by this treatment on RANTES, and the subpopulations of CD3+CD69+ and CD3+SLAM+ T cells in RSA patients.