Background: Early exposure to cow's milk (CM) proteins have been implicated in the pathogenesis of type 1 diabetes (T1D).
Objective: We analyzed the development of the humoral immune response to dietary CM proteins in early childhood and its relation to later T1D.
Subjects and methods: We studied a subgroup of 94 children randomized to be weaned to a CM-based infant formula in the trial to reduce insulin-dependent diabetes mellitus in the genetically at risk (TRIGR) pilot study. All subjects carried human leukocyte antigen-conferred T1D susceptibility and had an affected first-degree relative. After 7 years of follow-up, 8 subjects had progressed to T1D, 15 had at least one disease-associated autoantibody, and 71 remained autoantibody negative (controls). Immunoglobulin (Ig) G and IgA class antibodies to whole CM formula, beta-lactoglobulin (BLG), bovine serum albumin, and alpha-casein and IgG antibodies to bovine insulin (BI) were measured with enzyme-linked immunosorbent assays from sequential samples.
Results: The children with later T1D showed increased IgG levels to BLG from 3 to 18 months of age (p = 0.028) and enhanced IgA levels to CM formula at the age of 9 months (p = 0.022) compared with controls. In the children with an affected father or sibling, IgG antibodies to BI were higher in autoantibody-positive subjects than in autoantibody-negative subjects at 18 months of age (p = 0.022).
Conclusion: An enhanced humoral immune response to various CM proteins in infancy is seen in a subgroup of those children who later progress to T1D. Accordingly, a dysregulated immune response to oral antigens is an early event in the pathogenesis of T1D.