The effects of soluble products of activated lymphocytes and macrophages on blastocyst implantation events in vitro.

The purpose of this study was to investigate the effects of soluble products of activated lymphocytes and macrophages on mouse blastocyst attachment and trophoblast outgrowth in vitro. Hatched blastocysts were incubated with medium alone, supernatant fluids from mixed lymphocyte cultures (MLC), and with individual human and murine lymphokines and monokines in fibronectin-coated wells. Cultures were assessed at 24, 48, and 72 h for blastocyst attachment and trophoblast outgrowth. Both human and murine MLC supernatant fluids significantly enhanced trophoblast outgrowth in vitro. The cytokine, interleukin-1 beta (Il-1 beta), at a concentration of 10(3) U/ml, inhibited blastocyst attachment but significantly enhanced trophoblast outgrowth of attached blastocysts. Granulocyte, macrophage-colony-stimulating factor (GM-CSF) at a concentration of 250 U/ml significantly inhibited blastocyst attachment, while gamma interferon (gamma-IFN) at a concentration of 2.5 x 10(3) U/ml significantly inhibited trophoblast outgrowth and caused degenerative morphological changes in these cells. The results of this study indicate that products of activated immune cells may either facilitate or impede implantation events depending on the types of predominant cytokines present, their concentration(s), and the timing of their secretion relative to embryonic development.