REACTING THE ATOPIC WAY

Atopy results from pathogenic mechanisms which are now known to a significant extent, also at the molecular level. This knowledge has been prompted by genetic studies showing that total IgE levels are genetically controlled and that synthesis of IgE directed against selected allergens is associated to particular HLA alleles. Atopic patients predominantly produce certain cytokines (especially IL-4) which indeed favour the synthesis of IgE, rather than other cytokines (IFN-gamma) which antagonize IgE production. Degranulation of mast cells and basophils is facilitated in atopic subjects because IgE receptors are more represented on the membrane of mastocytes, basophils (and other cells) of atopic than of non-atopic subjects. Furthermore a greater production of mediators with activity of <<histamine releasing factors>> (HRF) carachterizes atopic patients. The genetically controlled production of certain cytokines which particularly stimulate eosinophils on one hand and the histaminic risk on the other, are further elements which underlie <<reacting the atopic way>>: in other words, the particular predisposition towards developing atopic manifestations on the part of subjects whose <<way of reacting>> is characterized by this combination of factors.