Comparative studies on tree pollen allergens. VIII. Immunological properties of the alder (Alnus incana) pollen extract.

The immunological properties of the aqueous crude alder pollen extract (AI crude) and gel filtration fractions AI 3, AI 4 and AI 34 (pool of fractions AI 3 and AI 4) were examined by immuno- and radioimmuno-electrophoretic techniques, RAST titration, RAST inhibition and skin prick tests (SPT). In CIE, the AI crude extract and AI 34 displayed reference precipitate patterns consisting of 27 and 24 visible Coomassie brilliant blue stained lines, respectively. The CRIE allergogram performed by incubation with 18 individual reaginic sera detected three IgE-binding antigens characterized by different IgE-binding properties. Antigen No. 7 (Ag 7) was demonstrated to be the major IgE antibody-binding antigen of alder pollen, while Ag 1 and Ag 11 were classified as intermediate allergens. The allergens of alder pollen were located in fractions AI 3 and AI 4 of the gel filtration chromatogram. Ag 7 was present in both fractions as demonstrated by FRIE with autoradiography (FRIEWA) on the gel filtration fractions and tandem-CRIE of AI 3 and AI 4. The CRIE allergogram, RAST, RAST inhibition and SPT demonstrated fraction AI 34 to be allergenically representative of the AI crude extract both qualitatively and quantitatively. Thus, fraction AI 34 was considered an optimal purified allergen extract of alder pollen, a suitable material for further biochemical characterization and trials on purification of the allergenic reactive antigens.