Immunoglobulin G receptors of intestinal brush borders from neonatal rats

Ciba Found Symp. 1983;95:287-99. doi: 10.1002/9780470720769.ch17.


Intestinal absorptive cells of the neonatal rat display on their brush border membranes receptors for immunoglobulin G (IgG) which function in selective transfer of maternal IgG. Our Scatchard analysis of [125I]IgG binding to isolated brush borders has corroborated the presence of two classes of specific binding sites (KA1 = 2.4 X 10(7) M-1 and KA2 = 3.7 X 10(5) M-1) and the increase in overall binding with decreased buffer concentration, as shown by Wallace & Rees 1980. However, our Scatchard analysis of binding at different buffer concentrations indicates that the only significant effect of lowered buffer concentration is to increase the number of low-affinity sites. Neither the number nor the affinity of the high-affinity sites is affected. Furthermore, brush borders from rats at 21 days have only the low-affinity sites and at this age the selective transfer of IgG has ceased. Morphological experiments with tracers for both light and electron microscopy suggest that the high-affinity sites correspond to the specific IgG receptors on the apical membrane. The majority of the low-affinity sites are found within the terminal web and are likely not to be involved in selective transport of IgG.

MeSH terms

  • Animals
  • Animals, Newborn
  • Biological Transport
  • Ferritins / metabolism
  • Intestine, Small / metabolism*
  • Microvilli / metabolism
  • Microvilli / ultrastructure
  • Rats
  • Receptors, IgG
  • Receptors, Immunologic / analysis*


  • Receptors, IgG
  • Receptors, Immunologic
  • Ferritins