Sllmmal~Type I allergy is a major health problem in industrialized countries where up to 15% of the population suffer from allergic symptoms (rhinitis, conjunctivitis, and asthma). Previously, we identified a cDNA clone that encoded a birch pollen allergen as profilin. Profilins constitute a ubiquitous family of proteins that control actin polymerization in eukaryotic cells; in particular, profilin participates in the acrosomal reaction of animal sperm cells. Although profilins had been unknown in plants so far, our finding led to the assumption that profilins might have similar functions in pollens during plant fertilization and therefore represent allergenic components in almost all pollens. We show that profilins are prominent allergens that can be isolated from tree pollens (Betula verrucosa, birch), from pollens of grasses (Phleum pratense, timothy grass), and weeds (Artemisia vulgaris, mugwort). About 20% of all pollen allergic patients tested (n = 65) displayed immunoglobulin E (IgE) reactivity to recombinant birch prolilin that was expressed in pKK223-3. An IgE inhibition experiment performed with recombinant birch profilin and purified natural profilins from timothy grass and mugwort indicates common IgE epitopes. Moreover, all pollen profilins purified from these far distantly related plant species, and likewise the purified recombinant birch profilin, are able to elicit dose-dependent histamine release via high affinity Fce receptor of blood basophils from profilin allergic patients. The presence of profdin and possibly related proteins as crossreacting allergenic components in various plants therefore provides an explanation as to why certain allergic patients display type I allergic reactions with pollens and even food from distantly related plants. A functional pan-allergen, like profilin, available as purified recombinant protein, may be a useful diagnostic and probably therapeutic reagent.
The purification of a 15 kD allergen from celery was obtained by a four step procedure. Evidence for at least two isoallergenic forms was obtained after analysis by two-dimensional-electrophoresis. A rabbit polyclonal antibody raised against this purified allergen allowed us to confirm our precedent results on the occurrence of allergenically and molecular mass-related components in celery and birch and mugwort pollens. In addition such components were also present in numerous other species like Cynodon dactylon, Sorghum halopense, Poa pratensis, Ambrosia elatior and in apple and carrot. The 15 kD allergen was identified as profilin by use of a specific rabbit polyclonal antibody that recognized a recombinant birch profilin. In addition, the purified celery allergen binds IgE from sera of patients allergic to birch profilin. These results reinforce the concept of profilin as a panallergen responsible in some patients for cross-allergic manifestations to various and unrelated species of grasses, weeds, trees, vegetables and fruits.
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