Methods: ImmunoCAP for specific IgE antibodies to cow’s milk and IgG4 antibodies to cow’s milk components Bos d 4 (alpha-lactalbumin), Bos d 5 (beta-lactoglobulin), Bos d 6 (bovine serum albumin; BSA), and Bos d 8 (caseins) were performed on sera collected before and after treatment with either cow’s milk elimination diet or fluticasone.
Results: In subjects treated with cow’s milk elimination diet, a reduction in IgG4 antibodies to alpha-lactalbumin, beta-lactoglobulin, BSA, and caseins was observed. Diet nonresponders (n=3/9) had higher levels of IgG4 antibodies to cow’s milk components at baseline compared to responders (n=6/9). There was a general increase in allergen-specific IgG4 antibodies in subjects with low to negative serum IgE to cow’s milk (i.e., <0.35 IU/mL). Conversely, serum IgG4 antibodies to cow’s milk components decreased, irrespective of treatment, in subjects with ≥0.35 IU/mL of IgE to cow’s milk.
Conclusions: The results indicate that IgG4 antibodies are often present in sera with low to undetectable IgE to the same protein, and that the response to cow’s milk avoidance is unrelated to IgE antibodies to cow’s milk components.