Atopic Dermatitis: Role of Food and House Dust Mite Allergens

Objective. The aim of this study was to evaluate the humoral immune response to cow milk (CM) protein, soya protein, and house dust mites in a group of 64 CM-fed infants, who had atopic dermatitis as the sole atopic manifestation, by measuring not only IgE but also specific IgG antibodies (Ab) against bovine β-lactoglobulin, soya flour aqueous extracts, and Der P1 antigens. Methods. A CM-free diet (Nan HA, Nestle) was given to these 64 CM-fed infants and the sensitivity to CM proteins was established by a positive challenge test with the offending food in improved infants. The serum was obtained just before the start of the CM-free diet, at the first consultation. The patients were classified into two groups according to their clinical response to the hypoallergenic formula. Results. Thirty-one infants (group 1) improved dramatically (positive challenge test), and 33 (group 2) did not improve with the exclusion diet but did improve after eviction of dust-producing items in the environment. The two groups were different in terms of their total IgE immunoglobulin concentration (higher in group 1, P < .05) and concentration of specific IgE Ab against CM protein (more frequent in group 1, P < .01). The IgG Ab concentrations against β-lactoglobulin, the major CM antigen (P < 10-4), and against soya protein (P < .01) were significantly more elevated in the group improved by the diet, with a threshold above which the response to the exclusion diet could be predicted as positive. On the contrary, the level of specific IgG Ab against house dust mites was four times higher in group 2 than in group 1. Twenty-nine of the 33 infants of group 2 improved after eviction of dust-producing items in the environment. Conclusions. It is proposed that specific IgG Ab concentrations against β-lactoglobulin, soya protein, and Der P1 antigen be determined in infants and children suffering from atopic dermatitis as a means of predicting the response to an exclusion diet, and a possible role of house dust mites in the pathogenicity of the disease is suggested.