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Human breast milk contains bovine IgG. Relationship to infant colic?
1Washington University School of Medicine, St Louis, Missouri.
Insights
Bovine immunoglobulin G (IgG) was detected in most human breast milk samples. Higher levels of bovine IgG were found in milk from mothers of colicky infants, suggesting a potential role in infant colic pathogenesis.
Area of Science:
- Immunology
- Pediatrics
- Gastroenterology
Background:
- Infant colic is a common condition with multifactorial causes.
- Previous research indicated an unidentified cow's milk protein, beyond beta-lactoglobulin and casein, may contribute to infant colic.
- Bovine immunoglobulin G (bovine IgG) is a potential candidate for this unidentified protein.
Purpose of the Study:
- To quantify bovine IgG levels in human breast milk.
- To compare bovine IgG concentrations in mothers of colicky versus non-colicky infants.
- To assess the presence of bovine IgG in infant formulas.
Main Methods:
- Radioimmunoassay was employed to measure bovine IgG concentrations.
- Human breast milk samples from 97 mothers were analyzed.
- Infant formula samples were also tested for bovine IgG content.
Main Results:
- Bovine IgG was detected in 88 of 97 (90.7%) tested mothers' milk samples.
- Mothers of colicky infants (n=29) had significantly higher median bovine IgG levels (0.42 µg/mL) compared to mothers of non-colicky infants (n=30, median 0.32 µg/mL) (P < .02).
- Cow's milk-based infant formulas contained bovine IgG levels (0.6–6.4 µg/mL) comparable to those found in human milk.
Conclusions:
- Significant levels of bovine IgG are commonly found in human breast milk.
- Elevated bovine IgG concentrations in breast milk are associated with infant colic.
- Bovine IgG may play a role in the pathogenesis of infant colic.
Abstract:
Previous studies have suggested that an unidentified cow's milk protein, other than beta-lactoglobulin and casein, might play a pathogenetic role in infant colic. Therefore, a radioimmunoassay was used to analyze human breast milk and infant formula samples for the presence of bovine IgG. Milk samples from 88 of the 97 mothers tested contained greater than 0.1 micrograms/mL of bovine IgG. In a study group of 59 mothers with infants in the colic-prone 2- to 17-week age group, the 29 mothers of colicky infants had higher levels of bovine IgG in their breast milk (median 0.42 micrograms/mL) than the 30 mothers of noncolicky infants (median 0.32 micrograms/mL) (P less than .02). The highest concentrations of bovine IgG observed in human milk were 8.5 and 8.2 micrograms/mL. Most cow's milk-based infant formulas contained 0.6 to 6.4 micrograms/mL of bovine IgG, a concentration comparable with levels found in many human milk samples. The results suggest that appreciable quantities of bovine IgG are commonly present in human milk, that significantly higher levels are present in milk from mothers of colicky infants, and that bovine IgG may possibly be involved in the pathogenesis of infant colic.