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Influence of the intestinal flora on the development of immune reactions in infants
Insights
Infants develop immunity to Escherichia coli O antigen through maternal antibodies and their own immune response starting at two months. Early colonization with specific E. coli serotypes can accelerate antibody production.
Area of Science:
- Immunology
- Microbiology
- Pediatrics
Background:
- Infants encounter Escherichia coli O antigen from birth, receiving maternal antibodies and initiating their own immune responses.
- The transition from maternal to infant antibody production is continuous, with detectable skin test sensitization around 2.5 months.
Purpose of the Study:
- To investigate the development of infant immune responses to Escherichia coli O antigen.
- To understand the timeline of antibody formation and sensitization in newborns.
Main Methods:
- Monitoring antibody levels and skin test responses in infants.
- Analyzing the impact of early colonization with specific E. coli serotypes.
Main Results:
- Infant antibody production begins around two months of age.
- Skin test sensitization to endotoxin occurs at approximately 2.5 months, correlating with serum antibodies.
- Colonization with a distinct E. coli serotype significantly enhances and accelerates antibody formation.
Conclusions:
- Infant immune systems gradually develop responses to E. coli O antigen.
- Early exposure to specific E. coli serotypes can prime a more robust and timely immune response.
Abstract:
Breast-fed and artifically fed infants are in contact with the O antigen of Escherichia coli from the first days after birth. From the mother, the infant obtains antibodies against nonpathogenic E. coli strains in low titer, and the infant begins to form its own antibodies during the 2nd month of life. The transition is known to be continuous even though the transferred antibodies could not be differentiated from the infant's own antibodies. Contact with endotoxin caused sensitization which was detected by the skin test at about 2.5 months, and thereafter the skin test data correlated with the presence of serum antibodies against endotoxin. The newborn infant can be colonized with a different E. coli serotype; such an antigenic stimulus evokes the formation of antibodies sooner and at a significantly higher titer than (i) the level of maternal antibodies transferred or (ii) the infant's antibodies normally formed later on against other random E. coli serotypes.