Demonstration of haemagglutinating antibody against food antigens in the amniotic fluid and cord blood.

1. Haemagglutinating antibody against egg white was demonstrated with higher incidence and with higher titres in the amniotic fluid than in sera obtained from the mother, cord blood, and newborn. On the other hand antibodies were barely detectable or absent from the meconium newborn infant's first voided urine. 2) In the amniotic fluid, haemagglutinating antibody was detected in highest titres against soybean and lactalbumin, respectively. 3) There was a similar trend of distribution of haemagglutinating antibody against egg white, lactalbumin or soybean in amniotic fluids from the same individual. 4) Haemagglutinating antibody against egg white in the amniotic fluid was identified as an immunoglobulin belonging to the IgM class; the possibility of the fetal origin of the haemagglutinating antibody in amniotic fluid was discussed.