Development of Immune Response to Cow's Milk Proteins in Infants Receiving Cow's Milk or Hydrolyzed Formula

Background: Development of humoral and cellular immune responses to orally administered antigens in human beings is poorly understood, although antigen administration has been suggested as a treatment for hypersensitivity disorders and autoimmune diseases.

Objective: The purpose of the study was to investigate the development of systemic immune response in infants fed with formula containing whole cow's milk proteins or hydrolyzed formula containing casein peptides.

Methods: In a double-blind trial, 10 infants received cow's milk-based formula, and 10 infants received a casein hydrolysate formula until the age of 9 months. Blood samples were taken at the ages of 6, 9, and 12 months. Cellular responses were assessed by proliferation assay of peripheral blood mononuclear cells to cow's milk proteins (beta-lactoglobulin, bovine serum albumin, and alpha-casein). Humoral responses to the same proteins were measured by ELISA for IgG antibodies.

Results: Feeding infants with cow's milk-based formula induced systemic humoral and cellular responses to cow's milk proteins. T-cell response later declined, supporting the concept of oral tolerization. Exposure to cow's milk proteins after the age of 9 months resulted in depressed cellular and humoral responsiveness to these proteins.

Conclusion: Our results support the view that induction of oral tolerance in human beings is an age-dependent phenomenon.