Microbial stimulation as an aetiologic factor in atopic disease

Epidemiologic evidence from various sources suggests that exposure to micro bial stimuli during early childhood can influence the induction and express ion of atopic diseases, particularly in the respiratory tract. Moreover, th ese effects may have long-lasting consequences in relation to expression of the atopic phenotype in adulthood. This review discusses key aspects of th is evidence in relation to the underlying mechanisms which regulate T-helpe r (Th)-cell function; in particular, the generation of Th-memory cells resp onsive to inhalant allergens.