Immunological basis for infantile immune deviation

Allergies manifest as an excessive reaction of the immune system to "normally" harmless environmental antigens. This errant reaction is determined be genetic factors as well as environmental effects in the broadest sense. Environmental factors play a decisive role. Clinical and epidemiological studies show that certain environmental factors (e. g., exposure to bacterial antigens) are associated with protection against allergies and asthma. On the other hand, a succession of environmental factors have been identified that induce allergenesis. Current studies increasingly indicate that this imprinting of the immune system and the induction of tolerance mechanisms are already determined very early in childhood development, including the gestational period. This article discusses some of the underlying immunological processes in connection with the establishment of allergic diseases in early childhood.