MHC-associated immunopotentiation affects the embryo response to teratogens

The present study was performed to evaluate whether the effect of environmental teratogens can be modified by maternal immunostimulation. Two chemicals, cyclophosphamide (CP) and 2,3-quinoxalinedimetanol, 1,4-dioxide (QD) were used as the reference teratogens (RT). The response to these RT was investigated in two animal models: (i) primigravid C57B1/6 mice who underwent intrauterine immunization with allogeneic paternal (CBA/J), third-party (BALB/c) or syngeneic male splenocytes 21 days before mating; (ii) C57B1/6 and CBA/J mice who were treated with RT during the second pregnancy only, after a different mating combination (syngeneic or allogeneic) in the first and the second pregnancy. Different doses of CP and QD were injected on days 12 and 9 of pregnancy, respectively. On day 19 of pregnancy implantation sites, resorptions, live and dead fetuses were recorded and live fetuses were examined for external and internal malformations with methods routinely used in teratological study. It was shown that intrauterine immunopotentiation with allogeneic paternal splenocytes clearly enhances the tolerance of F₁ embryos to RT. Thus, in CP-treated females the resorption rate and the proportion of malformed fetuses were significantly reduced. It was followed by an almost two-fold increase in fetal weight. The protective effect of such immunization in QD-treated females was manifested as a dramatic decrease of the proportion of malformed fetuses and the resorption rate. Syngeneic splenocytes could not significantly influence an embryo's sensitivity to RT. The response to RT was also significantly weaker in the second pregnancy of female mice mated twice allogeneically than that observed in allogeneically mated primigravid mice. These results show that the embryo's response to environmental teratogens may be influenced by fetomaternal immune interactions.