Specific IgG and IgA Antibodies and Related Subclasses in the Diagnosis of Gastrointestinal Disorders or Atopic Dermatitis Due to Cow's Milk and Egg

Abstract

Today the only investigation considered valid for the diagnosis of reactions to food is the oral stimulation test following a period of diet during which the suspected food item has been withdrawn. This test is, however, not without a certain risk, due to the possibility of the onset of an unexpected anaphylactic reaction. Researchers are therefore focusing attention on new, more reliable and less risky diagnostic techniques. The aim of this investigation was to evaluate, by means of ELISA, the serum levels of specific IgG and IgA antibodies and of their subclasses for casein, alpha lactalbumin, bovine beta-lactoglobulin and ovalbumin in 72 children with gastointestinal disorders or atopic dermatitis due to food. The diagnosis of food intolerance was made following a double blind oral stimulation test: 16 healthy age-matched children were used as controls. The results of the investigation demonstrated that specific IgA levels for all the food antigens were statistically higher compared with those of controls, irrespective of the clinical features, whereas the IgG class antibodies were statistically higher only for casein in the children with atopic dermatitis. Studies on the antibody subclasses, showed a statistically significant increase particulary of IgG, but also of IgA₁, especially in children with gastointestinal disorders. In conclusion, the results show that total specific IgA may play a role, although modest, in the diagnosis of food intolerance. The IgG subclasses, and to a lesser extent the IgA subclasses, appear to be useful in the diagnostic work-up, particularly in children with gastrointestinal symptoms.