Although the permeability of the intestine of the newborn infant to intact proteins has been the subject of investigations for at least 30 years, the literature remains equivocal. An understanding of this phenomenon has implications which concern allergic states, the prophylactic role of breast feeding, and the physiology of the gastrointestinal tract of the newborn.
Recently, Abbas and Tovey1 have suggested that antibodies may be secreted into the amniotic cavity, swallowed by the fetus, and absorbed from the gut. This suggestion was based on observations that newborn infants with esophageal atresia have gamma-globulin concentrations only about 40% as high as those found in normal newborn infants. If this study is confirmed, it is not unreasonable to suppose that the intestine of the newborn might also be capable of absorbing gamma-globulins.
Attempts have been made to assess the human infant's ability to absorb immunologically intact proteins from the intestinal lumen.
LEISSRING JC, ANDERSON JW, SMITH DW. Uptake of Antibodies by the Intestine of the Newborn Infant. Am J Dis Child. 1962;103(2):160-165. doi:10.1001/archpedi.1962.02080020166009