Immunoglobulins in Feces from Infants Fed Human or Bovine Milk

Abstract

Concentrations of human immunoglobulins in extracts of feces from infants receiving human milk were higher than in feces from infants fed bovine milk. This was most valid for IgA. The antibody activity, tested with agglutinins to rabbit erythrocytes as markers, was also higher in feces from 1‐month‐old infants fed human milk than in feces from infants given bovine milk. No difference in agglutinin activity was found later in infancy, Isoagglutinins in human milk to blood group antigens A and B were recovered in feces from infants receiving this milk, regardless of the infants' own blood group. Gel filtration studies, as well as inhibition of agglutination and antiglobulin test, gave evidence that IgA was largely responsible for the fecal agglutinin activity. Unlike human milk in which also IgM reacted with rabbit erythrocytes, shown by immunization of rabbits, only IgA in the fecal extracts seemed to have such activity. IgA antibodies in human milk will thus retain some of their activity with passage through the infant gut