Histamine releasing factor (TCTP) is an auto-reactive IgE-binding antigen in patients allergic to Cladosporium herbarum

Abstract

Rationale Cladosporium herbarum ( C. herbarum) is one of the most important and world wide occurring allergenic fungal species. Sensitization to C. herbarum (and fungi in general) has often been associated with asthma, chronic idiopathic urticaria, and allergic dermatitis. It is therefore interesting to define the allergen repertoire of C. herbarum. We have undertaken here to characterize a new Cladosporium allergen, which was isolated from a cDNA library of C. herbarum spores and mycelia and to compare it with its human homologue. Methods A C. herbarum cDNA library constructed in the lambda-ZAP vector was screened with sera of patients allergic to Cladosporium. The newly isolated cDNA clone and its human homolog were expressed in E. coli, purified to homogeneity and immunologically analyzed by IgE blots. Results The characterized allergen is a close homolog of the human histamine releasing factor (TCTP). IgE antibodies of three of five patients, which recognize the Cladosporium allergen, also recognize the human protein in immune blots. Conclusion The new allergen will not only contribute to define more comprehensively the allergen repertoire of C. herbarum, it also allows us to test the role of a new auto-antigen with a possible role in certain severe forms of allergic disease.