Role of carbohydrate moieties in cross-reactivity between different components of Parietaria judaica pollen extract.

Cross-reactivity between the different components in Parietaria judaica pollen extract has been investigated by polyclonal as well as monoclonal antibodies before and after chemical deglycosylation obtained by trifluoromethanesulphonic acid (TFMS) treatment of the extract. In western blotting a polyclonal rabbit antiserum, obtained by injecting purified Par j I, was able to recognise many components of the native extract. However, its reactivity was restricted, after chemical deglycosylation of the extract, to the major allergen alone, indicating that its cross-reactivity was due to sugar moieties. Moreover, out of several monoclonal antibodies raised by injecting the whole Parietaria judaica extract, one (1A4/2F8) was also able in western blotting to recognise an epitope shared by many components of the extract except the major allergen Par j I. However, in this case the broad reactivity of the antibody was not affected by the deglycosylating procedure. When the reactivity of Parietaria judaica extract was tested before and after sugar removal, against specific IgE from a pool of patient sera, no differences could be demonstrated, thus indicating that carbohydrates are not strongly involved in the binding of Parietaria judaica-specific IgE. The results indicate that both proteic and carbohydratic cross-reactive epitopes are shared by many components of Parietaria judaica pollen extract.

Use of monoclonal antibodies for the characterization of allergenic extracts.

The diagnosis of allergic diseases is commonly carried out by using poorly standardized preparations containing allergenic and non-allergenic components. Recently, monoclonal antibody technology has been applied to the biochemical characterization and to the purification of allergens, in order to evaluate their potential role in the standardization of diagnostic and therapeutic extracts. Three main results have been achieved: 1) the characterization of allergenic epitopes recognized by IgE and IgG from patients' sera; 2) the purification by affinity chromatography of relevant allergenic components; 3) the development of immunoassays for the quantitation of allergens in the commercially available extracts used for diagnosis and therapy.