Intestinal absorption of IgA in the newborn.

The aim of this study was to establish whether or not the newborn can absorb IgA from colostrum, using two feeding regimens. Single radial immunodiffusion on commercial Behring plates was used for IgA quantitation. In group A, 30 mature newborn infants born by vaginal delivery and fully breast fed, cord serum IgA concentration was 0.0990 +/- 0.0294 mg/ml (means +/- SEM). IgA was detectable in 9 of 30 infants. On the 3rd day of life, IgA concentration in serum was 0.3610 +/- 0.0194 mg/ml (means +/- SEM). It was detectable in all 30 infants; on the 5th day of life, its concentration was 0.4293 +/- 0.0365 mg/ml (means +/- SEM). In group B, 39 newborn infants born by cesarean section and fed boiled human milk exclusively, IgA was not detected either in cord, or in venous blood on the 3rd and 5th day of life. The rise of serum IgA in breast-fed newborn infants, highly significant from the 1st to the 3rd day of life (p less than 0.0001), and its increase between the 3rd and 5th day, although not significant, was in distinct contrast to the undetectable serum IgA in newborn infants fed boiled human milk. These data strongly suggest that IgA absorption from colostrum occurs at least until the 3rd day of life.