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Development of intestinal mucosal immunity in fetal life and the first postnatal months
T O Rognum1, S Thrane, L Stoltenberg
1Institute of Forensic Medicine, University of Oslo, National Hospital, Norway.
Insights
The developing infant intestine shows rapid maturation of secretory component (SC) and immune cells after birth. This suggests environmental factors shape the intestinal immune system early in life.
Area of Science:
- Immunology
- Gastroenterology
- Neonatology
Background:
- The development of the intestinal immune system is crucial for infant health.
- Understanding the timeline of immune component maturation in the infant duodenum is essential.
Purpose of the Study:
- To investigate the developmental expression of secretory component (SC) and human leukocyte antigen (HLA) determinants in the infant duodenum.
- To characterize the presence of immunoglobulin (IgA, IgM, IgG)-producing immunocytes in the developing infant gut.
Main Methods:
- Immunohistochemistry was used to analyze duodenal tissue from infants across different gestational ages and postnatal periods.
- Expression of SC, epithelial HLA class I and II, and IgA, IgM, and IgG immunocytes were assessed.
Main Results:
- Secretory component (SC) expression increased significantly after 29 weeks gestation, reaching adult levels by 1 week postpartum.
- Epithelial HLA class I was present throughout, while HLA class II (DR) appeared after 1 week postnatal.
- IgA immunocytes were absent before 1 week postnatal, contrasting with the presence of IgM and IgG cells.
Conclusions:
- The infant duodenum undergoes significant maturation of SC, HLA-DR expression, and IgA-producing cells shortly after birth.
- These changes indicate that the intestinal immune system is influenced by environmental factors in the early postnatal period.
Abstract:
Nine premature infants who were either stillborn or who died shortly after delivery (gestational age, 24-32 wk), eight full-term infants who died during the first 3 postnatal wk, and four infants who died in the postneonatal period were studied by immunohistochemistry for duodenal expression of secretory component (SC) and epithelial HLA class I and II determinants and for the presence of IgA-, IgM-, and IgG-producing immunocytes. Only small amounts of SC appeared before the 29th gestational wk, but thereafter it increased rapidly; 1 wk after birth, SC showed an adult distribution pattern. Epithelial class I was expressed throughout the period investigated, whereas class II (HLA-DR) determinants were absent on the duodenal villi until 1 wk after birth. HLA-DP and -DQ were not expressed by the epithelium. No IgA immunocytes were seen before 1 wk after birth, whereas a few IgM- and IgG-producing cells were present throughout the period studied. The intense epithelial HLA-DR expression from the 2nd postnatal wk, along with SC and the appearance of IgA immunocytes, suggests that the intestinal immune system is modulated in response to environmental factors shortly after birth.