DEVELOPMENT OF LONG-TERM TOLERANCE VERSUS SENSITIZATION TO ENVIRONMENTAL ALLERGENS DURING THE PERINATAL-PERIOD

Evidence is steadily accumulating which indicates that the patterns of T cell reactivity against the environmental antigens that determine t he allergen responder phenotype in adulthood are, in many cases, estab lished during infancy. The underlying regulatory processes which deter mine the nature of long-term immunological memory against these antige ns appear to involve a combination of classical high zone and low zone tolerance mechanisms. It appears likely that these T cell responses a re initiated before birth via the transplacental transfer of low level s of allergen to which mothers are exposed during pregnancy.