Identification of a Hevea brasiliensis latex manganese superoxide dismutase (Hev b 10) as a cross-reactive allergen

Background: Cross-reactive allergens play an increasingly important role in latex allergy in complicating both the diagnosis and time course of allerg ic symptoms. Manganese superoxide dismutase (MnSOD), a ubiquitous protein o f prokaryotic and eukaryotic organisms, was described as a cross-reactive a llergen in Aspergillus fumigatus. Little information is available on the im portance of this pan-allergen in Hevea brasiliensis latex. The aim of this study was to clone and express MnSOD from H. brasiliensis latex, and to obt ain the soluble and immunologically active recombinant allergen for diagnos is of latex allergy and to investigate possible cross-reactivities with the structurally related A. fumigatus and human MnSODs. Methods: A complementa ry DNA coding for Hevea latex MnSOD was amplified by PCR. The recombinant p rotein was produced in Escherichia coli with an N-terminal hexahistidyl tag . Enzymatic activity of the recombinant protein was determined using an enz yme assay for SODs. IgE immunoblotting and IgE inhibition assays were perfo rmed to characterize the recombinant allergen and its cross-reactivity. Res ults: A Hevea latex MnSOD consisting of 206 amino acid residues was cloned and expressed in E. coli. The allergen was designated Hev b 10. The recombi nant protein was enzymatically active, indicating the correct folding of th e protein. In immunoblots, latex- as well as A. fumigatus-allergic patients revealed IgE binding to recombinant (r)Hev b 10. Cross-reactivity to Asp f 6, the MnSOD from A. fumigatus, and human MnSOD was determined by inhibiti on of IgE binding to these MnSODs by rHev b 10. Conclusions: Hev b 10 is a new cross-reactive allergen of H. brasiliensis which belongs to the 'latex- mold' group of latex allergens. Furthermore, it is a candidate for primary sensitization in patients allergic to the pan-allergen MnSOD. Copyright (C) 2001 S. Karger AG, Basel.