Synergistic effect of subteratogenic doses of antisera on the development in the rat

Wistar rats were administered rabbit anti-rat-umbilical-cord serum (AUCS) alone on day 9 of gestation or in combination with subteratogenic doses of rabbit anti-rat-kidney serum (AKS). The results showed that the incidence of malformation was low (13.1% +/- 7.0 S.E.) even when very high doses of AUCS alone were administered. However, the incidence markedly increased to 61.0% +/- 9.3 S.E. when a small dose (0.10 ml/100 gm) of AKS was administered on day 9 followed by 0.90 ml/100 gm of AUCS on day 10. The malformations included microphthalmia, hydrocephaly, aortic arch anomalies, ventricular septal defect, and anophthalmia, being similar to the effects of a medium dose of AKS. These results suggest that a combination of subteratogenic doses of teratogenic antisera produces malformations, possibly by mechanisms that potentiate the teratogenic action of the sera.