[Antiviral activity of the human amniotic fluid and placenta]

Antiviral activity (3-24 IU/ml) was detected in the amniotic fluid of 21 of 25 pregnant women examined (84%) by conventional interferon assay using human amniotic cells (WISH) and vesicular stomatitis virus. The pregnancies were from 16 to 42 weeks gestation without obvious viral infection or other complications. The antiviral substance in the amniotic fluid seems to be interferon alpha, because it was not inactivated by heat (56 degrees C, 30 min) or acid (pH 2.0, 24 hrs.) and it was inactivated by anti-human interferon alpha neutralizing serum. Neither the incidence nor the titer of the activity in amniotic fluid has any relationship with gestational age, age of the pregnant women or parity. Antiviral activity (4-32 IU/10 mg protein/ml) was also detected in the placenta homogenate of 23 of 25 pregnant women examined (92%). The pregnancies were from 7 to 41 weeks of gestation with or without complication. The titer of antiviral activity was relatively high in the placenta of babies with central nervous system anomalies and it was low in the placenta of intrauterine growth retardation pregnancies, compared with normal pregnancies. The activity in the placenta was not inactivated by heat (56 degrees C, 30 min), acid (pH 2.0, 24 hrs.), anti-human interferon alpha neutralizing anti-serum or anti-human interferon beta neutralizing anti-serum.