Specific humoral response to cows' milk proteins and ovalbumin in children with atopic dermatitis.

Serum antibodies to four common food antigens, three cows' milk proteins (casein, alpha-lactalbumin and beta-lactoglobulin) and ovalbumin, were investigated in 21 children with atopic dermatitis (aged 3 months to 3 years) and in 15 age-matched healthy controls. Specific IgE was measured by radioallergosorbent test; an ELISA was developed to detect specific IgG, IgG subclasses and IgA. Specific IgE was found in 76% of patients, while antigen-directed IgG and IgA were present both in patients and healthy controls; IgG to ovalbumin and IgA to alpha-lactalbumin were significantly higher in children with atopic dermatitis. The analysis of the IgG subclass distribution showed different patterns of response, IgG1 and IgG4 being higher in patients (even though statistically significant only for ovalbumin), and IgG2 and IgG3 being lower in this group. The presence of food-specific IgE in the majority of atopic children and the different specific IgG subclass patterns observed in patients and controls may reflect an alteration in the immune response to dietary proteins in atopic dermatitis.