Immunoneutralization of endometrial monoclonal nonspecific suppressor factor beta (MNSFbeta) inhibits mouse embryo implantation in vivo.

Successful embryo implantation and pregnancy in mammals depends on the establishment of immune tolerance between the maternal immune system and fetal cells. Monoclonal nonspecific suppressor factor beta (MNSFbeta), a cytokine produced by suppressor T cells in various tissues, possesses an antigen-nonspecific immune-suppressive function, and may be involved in the regulation of the uterine immune response during embryo implantation. In this study, anti-MNSFbeta IgG administered directly into the uterine lumen, significantly inhibited mouse embryo implantation in a dose-dependent manner in vivo, and this effect was reversed by co-administration of recombinant MNSFbeta. The effects of anti-MNSFbeta IgG on the gene pattern profiles in mouse uterine tissues were examined by cDNA microarray and several changes were confirmed by real-time PCR. Anti-MNSFbeta IgG caused up-regulation (> or = 2-fold) of 71 known genes and 17 unknown genes, and decreased expression (> or = 2-fold) of 74 known genes and 43 unknown genes, including several genes previously associated with embryo implantation or fetal development. Most of the known genes are involved in immune regulation, cell cycle/proliferation, cell differentiation/apoptosis, and lipid/glucose metabolism. These results demonstrate that MNSFbeta plays critical roles during the early pregnancy via multiple pathways.