TERATOGEN-INDUCED APOPTOSIS MAY BE AFFECTED BY IMMUNOPOTENTIATION

Intra-uterine immunization of mice with paternal allogeneic or xenogen eic (rat) splenocytes was found to increase embryo tolerance to cyclop hosphamide (CP)-induced teratogenesis. As the CP-induced teratogenic e ffect was shown to be associated with apoptosis, the present study was designed to investigate whether the protective effect of immunopotent iation may be realized via an alteration of CP-induced apoptosis. Vari ous doses of CP were injected intraperitoneally into ICR mice on day 1 2 of pregnancy. Intra-uterine immunization with xenogeneic rat splenoc ytes was carried out 3 weeks before mating. Implantation sites, resorp tions, live and dead fetuses, as well as soft tissue anomalies and ext ernal malformations, were recorded to evaluate the CP-induced embryoto xic effect. In parallel, flow cytometric analysis and DNA fragmentatio n assay were used for evaluation of CP-induced apoptosis in limbs, tai l and whole embryos. The treatment of mothers with a high dose of CP i nduced the death of almost all embryos and striking fetal growth retar dation in survivors, This strong embryotoxic effect was accompanied by very prominent DNA degradation in cells collected from whole embryos. Immunostimulation caused a dramatic decrease of embryonal loss (by si milar to 50%) and a significant (about 30%) increase in fetal weight. Such an increase in fetal survival and in fetal weight was found to be accompanied by a clear decrease in apoptosis level in embryo cell pop ulations as judged by DNA gel electrophoresis with subsequent quantita tion of DNA Fragmentation in negatives by an image analysis technique. After treatment with a low dose of CP, a decrease in the proportion o f fetuses with limb and tail anomalies in immunized females was accomp anied by a decrease in the proportion of apoptotic nuclei in cells tak en from Limbs and tails. The results of this study suggest that the te ratogen-induced apoptosis may, at least partly, be dependent on fetoma ternal immune interactions.