LYMPHOKINE PRODUCTION BY DECIDUAL CELLS IN ALLOGENEIC AND SYNGENEIC MURINE PREGNANCY

The importance of T cells during pregnancy has been well established in the murine system. Depletion of CD4 and/or CD8 positive cells from the maternal circulation increases fetal abortion and inhibits placental and fetal growth. T cell mediated regulation depends on T cell-derived lymphokines such as IL-6, IL-10, GM-CSF and IL-3. Among these factors, GM-CSF and IL-3 have been shown not only to stimulate trophoblast growth but also to promote placental function. All these growth factors having a short half life in vivo must exert their effect proximally to the site of production. In the present study, biologically active GM-CSF and IL-3 produced by T cells in the maternal decidual cap, which is the closest to the feto-placental unit maternal component, was detected. Cytoplasmic staining of totla decidual cap cells in various strain combinations, usng monoclonal antibodies to lymphokines, showed that the numbers of cells producing these factors vary depending on the day of pregnancy and on the strain combination used. Using indicator cell lines and neutralizing antibodies, it was seen that GM-CSF and IL-3 are produced at the eleventh day of pregnancy and secreted in both allogeneic and syngeneic pregnancies by decidual cap cells. T cell depletion experiments in vivo showed that these factors are produced by T lymphocytes. The production and secretion of biologically active CSF-1 was also evaluated in ths study. Although this is not a T cell-derived lymphokine, it is shown to be produced in the uterus and affect trophoblast growth. The results indicate that on the eleventh day of pregnancy only syngeneically pregnant mice produce sufficient quantities of CSF-1 to stimulate biologic activity. It is therefore demonstrated that the maternal immune system stimulates the growth of the feto-placental unit, obeying different rules in allogeneic and syngeneic pregnancy. © 1993 Academie Press Limited.