The Intestinal Microflora in Allergic Patients

Abstract

The immune system at birth is not adapted for postnatal life in several respects and the postnatal maturation of the immune system is characterised by the development of a balanced Th1/Th2 immunity. The efficiency and kinetics of this process is slower in atopic children. According to “hygiene hypothesis, ” modern living is associated with too little microbial stimulation early in life. This lack of stimulation of the immune system would in turn result in deficient down-regulation of immune responses to those ubiquitous allergens that the individual encounters early in life. It is likely that the primary signal for such maturation during infancy and early childhood is provided not by pathogens, but by stimulation from the commensal microbial flora, as the gut flora is the quantitatively most important source of microbial stimulation. Differences in the composition of the gut flora are demonstrable very early in life and even before the development of any clinical manifestations of atopy. As the microbial flora is driving the maturation of the immune system, changes in its composition, as a consequence of an altered lifestyle and diet in industrialised societies, my play a role for the higher prevalence of allergy. Clinical trials lend support to the concept that the intestinalmicroflora may have an important role for the immune regulation to allergens and that certain probiotic strains could be used for the treatment of allergy, or even the prevention of disease.