CSF-1 induces resorption of embryos in mice.

We have shown previously that C57BL/6J female mice inoculated with the syngeneic BL6-T2 regressor tumor resorb a high proportion of embryos sired by B6D2F1 or DBA/2 males but not embryos engendered by CBA/J or C57BL/6J males. In this present report, we provide a mechanism elucidating the nature of the fetal wastage observed. It was found that the BL6-T2 tumor secretes constitutively GM-CSF and CSF-1. Based on the hypothesis that those cytokines could interfere with normal fetal development, we injected semi-purified GM-CSF or CSF-1 into pregnant females, for five days. Results show that CSF-1 was able to induce a high rate of fetal resorption whereas GM-CSF had no effect.