IL-4 AS A KEY FACTOR INFLUENCING THE DEVELOPMENT OF ALLERGEN-SPECIFICTH2-LIKE CELLS IN ATOPIC INDIVIDUALS

In the last years Th2-like cells, able to produce IL-4, IL-5, IL-6 and IL-10, have been shown to play an important role in the pathogenesis of allergic diseases. They are absolutely required for Ige production by B-cells and are expanded at the level of target tissues of atopic p atients. Very recently, much attention has been focused on the genetic and environmental factors responsible for the differentiation and ong oing expansion of allergen-specific Th2-like cells in atopic subjects. In this review possible cellular sources of IL-4 in the primary, seco ndary and ongoing responses to allergens are discussed. In atopics, Th cell precursors themselves could be proposed as a main source of IL-4 in the primary responses to allergens. However, there is extensive ev idence for the role of other cells such as mast cells, basophils and e osinophils as important sources of IL-4 in the secondary and ongoing r esponses to allergens.