Specific immunotherapy.

Increase of the prevalence of allergy these last 20 years is in parr second ary to the modification of the allergenic charge of our environment, The sp ecific immunotherapy (SIT) is the only etiologic treatment of the allergic disease and numbers of authors believe that, for the future, this treatment could change the natural history of the respiratory allergy, provided that it is realised early in the first years of life. Several experimental stud ies show that the process of the SIT could be the restoration of the Th1 ce ll/Th2 cell balance which is reversed in allergies. However, indications of SIT have to be carefully selected. The ideal indication is the single sens itized asthma, and treatment has to be started in the first years of life, at the onset of the asthmatic disease, before a definitive remodelling of t he respiratory airways induced by inflammation. Subcutaneous SIT is for the moment the only effective route confirmed by several controlled trials, in particular for grass pollens, possibly for house dust, pet danders and mit e allergens. Risk of syndromic effects, present all the time of the SIT pro tocol, can be prevented by rigorous use of the SIT according to the Europea n consensus. The advent of recombinant allergens, in particular by compleme ntary DNA (cDNA) modified by site-directed mutagenesis, could tip the immun e response to a Th-1 like response instead of a Th-2 like response (IgE med iated) and result in a better tolerated and more efficacy immunomodulation. (C) 1999 Elsevier, Paris.