Recombinant allergens: application to diagnostic and therapeutic perspectives

Techniques of generic engineering applied to allergens have enabled the pro duction of recombinant allergens. The validation of recombinant allergens i mplies that their immunological activity and their identity with natural al lergens might be confirmed by in vitro and in vivo techniques carried out o n a sufficiently large number of allergic subjects. Currently available res ults for the principal pneumoallergens are reported. Thus the work of valid ating recombinant allergen BeTv1 has been confirmed by in vitro tests and a lso by skin tests and nasal and bronchial provocation tests. The associatio n of four recombinant allergens of phleole has enabled the detection in vit ro of sensitisation to germinated pollens in 94.5% of patients. For mites t he validity of group 2 recombinant allergens has been confirmed. A system e nabling the expression of glycosylation of recombinant proteins was necessa ry to validate recombinant proteins in group 1 allergens. The recombinant a llergen Blot5 is recognised as bring effective in the detection of sensitiz ation to Blomia tropicalis, a domestic allergen in sub tropical countries. The recombinant allergens Bla g 4 and Bla g 5 have been tested in vitro and in vivo and reactions were positive in nearly 50% of subjects sensitive to cockroaches. The recombinant Asp f 1 has been tested in subjects suffering from allergic bronchopulmonary aspergillosis and is positive in 60-85% of cases. Some studies are available for recombinant allergens of certain animal anti gens (Equ c 1, Bos d 2). The consequences of clarifying recombinant allerge ns are then analysed : obtaining better standardised allergens for diagnost ic tests, studying the spectrum of specificities of IgE induced by an aller gen, the quantification of specific IgE, a better approach to mixed allergi es with the help of recombinant allergens of the principal mixed allergens. Some recent progress has led to the production of modified recombinant all ergens: the synthesis of recombinant polypeptides corresponding to T epitop es, the production of isoform recombinant allergens with reduced allergenic activity, the production of recombinant allergens of modified allergenic m olecules by directed mutations and the production of recombinant fragments of allergenic molecules. The use of modified recombinant allergens is a way of permitting research which would, in the future, lead to new modalities of specific immunotherapy.