Different role of secretory IgA in the pathogenesis of RAST-positive and RAST-negative atopic dermatitis.

Secretory-IgA (SIgA) concentrations were determined in whole saliva, unstimulated or stimulated by lemon juice, of thirty-eight children with atopic dermatitis, which comprised three adolescents, sixteen with IgE detected by RAST to one or more common allergen and twenty-two without specific IgE by RAST. There were thirty healthy controls matched for age and sex. The mean amount of total IgE was significantly greater in the RAST-positive than in the RAST-negative group. The mean SIgA concentration in unstimulated saliva of the RAST-positive atopic dermatitis group was less than that of the RAST-negative atopic dermatitis group and control groups, through the mean concentrations of SIgA of stimulated saliva were not significantly different in the three groups. It is suggested that the pathogenesis of atopic dermatitis may differ in children with or without specific-IgE antibodies; in those who were RAST-positive deficient exclusion of allergen by the intestinal barrier contributed to the pathogenesis, but not in those who were RAST-negative.