A human monoclonal IgE antibody defines a highly allergenic fragment of the major timothy grass pollen allergen, Phl p 5: Molecular, immunological, and structural characterization of the epitope-containing domain

作者：Flicker S; Vrtala S; Steinberger P; Vangelista L; Bufe A; Petersen A; Ghannadan M; Sperr WR; Valent P; Norderhaug L; Bohle B; Stockinger H; Suphioglu C; Ong EK; Kraft D; Valenta R^*

来源：The Journal of Immunology, 2000, 165(7): 3849-3859.

Almost 90% of grass pollen-allergic patients are sensitized against group 5 grass pollen allergens. We isolated a monoclonal human IgE Fab out of a combinatorial library prepared from lymphocytes of a grass pollen-allergic patient and studied its interaction with group 5 allergens. The IgE Fab cross-reacted with group 5A isoallergens from several grass and corn species. By allergen gene fragmentation we mapped the binding site of the IgE Fab to a 11,2-kDa N-terminal fragment of the major timothy grass pollen allergen Phl p 5A, The IgE Fab-defined Phl p 5A fragment was expressed in Escherichia coli and purified to homogeneity, Circular dichroism analysis revealed that the rPhl p 5A domain, as well as complete rPhl p 5A, assumed a folded conformation consisting predominantly of an cu helical secondary structure, and exhibited a remarkable refolding capacity. It reacted with serum IgE from 76% of grass pollen-allergic patients and revealed an extremely high allergenic activity in basophil histamine release as well as skin test experiments. Thus, the rPhl p 5A domain represents an important allergen domain containing several IgE epitopes in a configuration optimal for efficient effector cell activation. We suggest the rPhl p 5A fragment and the corresponding IgE Fab as paradigmatic tools to explore the structural requirements for highly efficient effector cell activation and, perhaps later, for the development of generally applicable allergen-specific therapy strategies.

• 出版日期2000-10-1