IgG exchange as a means of partial correction of anomalies in rat embryos in vitro, induced by sera from women with recurrent abortion

Many recurrent abortions have an unknown aetiology. A significant proportion of sera from women with spontaneous abortions induced 50% or more anomalies ('high risk' sera) in cultures of 10.5-day-old rat embryos. Because it is assumed that the teratogenic factor(s) in recurrent abortion is often an immunoglobulin G (IgG) antibody, it was attempted to reduce the rate of anomalies induced by high risk sera by removing the IgG fractions and adding IgG fractions from control sera (sera from women in a normal second trimester of pregnancy and after delivery). Concomitantly, an attempt was made to induce anomalies in embryos cultured in control sera by adding IgG fractions from high risk sera. It was found that among the high risk sera there were three groups, according to the response to the IgG exchange: (1) a group in which IgG exchange 'corrected' the anomalies in high risk sera, whereas it induced anomalies in control sera; (2) a group in which anomalies were found both in embryos cultured in high risk sera and those cultured in control sera; (3) a group in which the IgG exchange did not affect the results in the 'experimental' or 'control' embryos. Examination by transmission electron microscopy, of yolk sacs cultured in sera with IgG from women belonging to the third group did not reveal ultrastructural changes. In conclusion, in some high risk sera the teratogenic factor appears to be an IgG only; in others, teratogenicity is brought about not only by an IgG, but also by additional teratogenic factor(s); in the last group, the teratogenic factor(s) does not appear to be an IgG at all.