Evolution in the understanding of cross-reactivities of respiratory allergens: The role of recombinant allergens

The aim of this review is to show the impact of the use of purified and rec ombinant allergens to discriminate between co- and cross-sensitization to r espiratory allergens. The author describes the evolution of diagnostic test s over the last decades; the tests initially allowed the detection of simul taneously positive cutaneous tests and/or simultaneous positivity of specif ic IgE to different allergen extracts, but they did not differentiate cross -sensitization from co-sensitization. RAST inhibition studies with crude ex tracts then established cross-reactivity, but did not identify the cross-re active allergens involved. Later, immunoblot and CRIE inhibition were able to detect multiple cross-reactive allergens and to assess their physicochem ical properties. But it is only since purified and recombinant allergens ha ve been used in the different investigations that identification of crossre active allergens has been made possible at a molecular level. This historic al approach is illustrated by examples selected from some of the main respi ratory allergen sources: tree pollen, grass pollen, weed pollen, acarids, c ockroaches and mammalians. For each of these allergen sources, the author g ives an updated presentation of major and minor cross-reactive allergen mol ecules and refers to the last decade's major publications concerning immuno chemical investigations carried out in the field of cross-reactive respirat ory allergens. Emphasis is placed on the clinical applications for allergic patients: improvement in the accuracy of the diagnosis of sensitization, n ew concepts of immunotherapy based on genetically engineered hypoallergenic variants of cross-reactive allergens used alone or in combination, evaluat ion of allergen load with environmental tests using monoclonal antibodies a gainst cross-reactive allergens. Copyright (C) 2000 S. Karger AG, Basel.