In children suffering from food allergy the microecology of the gut and the immune status were examined. As a rule, sensitization due to the penetration of the epithelial barrier of the intestinum by macromolecules of the food is not accompanied by deficiency of secretory IgA. In all cases dysbacteriosis of different degree was observed with a characteristic picture of deficiency of Bifidobacteria and Lactobacilli combined with rising numbers of Enterobacteriaceae. Correlations to an altered immune response are obvious.

Breast-feeding is of high importance for the development of intestinal eubiosis. Before beginning with breast-feeding the coprofiltrates of newborns lack of IgA. Following the first feeding IgA concentration in the faeces sharply increases (up to 200 mg/100 g faeces). Comparable high values can be found in the coprofiltrates of breast-fed sick prematures. In the coprofiltrates of artificially fed healthy newborns and sick prematures no IgA is provable, within the first two weeks of age. Afterwards both the frequency of its evidence and its concentration gradually rise. This can be regarded as a sign of an increasing local production of immune proteins. Starting with the second year of life, only, the values of all the immunoglobulins fall again. It happens a microbial degradation. Increased concentrations of immunoglobulins in the coprofiltrates of children over 3 years must be evaluated as a sign of subclinical dysbacteriosis.