Identification and Characterization of Cross-Reactive Natural Rubber Latex and <i>Ficus benjamina </i>Allergens

Abstract

Background: An association between allergy to Ficus benjamina and natural rubber latex (NRL) has been suspected based on clinical and immunological observations. The responsible cross-reactive allergens have not been identified yet. This study was undertaken to investigate the cross-reactivity between hevein (Hev b 6.02, 4.7 kD), a major allergen of NRL, and F. benjamina and identify its counterpart in F. benjamina. Methods: 89 serum samples from subjects allergic to NRL were used in the study. Skin prick tests were performed with highly purified hevein and sap extract of F. benjamina. Specific IgE antibodies to NRL, F. benjamina and Hev b 6.02 were determined by the Pharmacia CAP method. Cross-reactivity among these allergens was investigated by means of CAP and immunoblot inhibition experiments. Two-dimensional gel electrophoresis separation and protein microsequencing were performed to identify the cross-reactive allergens in F. benjamina. Results: 67 out of 89 (75%) sera showed elevated IgE to hevein. Specific IgE to Ficus were found in 22 (24.7%) sera, and with 1 exception, all these sera also had IgE to Hev b 6.02. Results of CAP inhibition assays using 11 sera showing IgE to both Hev b 6.02 and Ficus demonstrated that the IgE to Ficus could be completely inhibited by Hev b 6.02 in 6 of 11 sera. Immunoblots and immunoblot inhibition assays revealed that a protein of about 45 kD in F. benjamina is strongly recognized by serum IgE. In addition, the IgE-binding reactivity to this 45-kD protein could be completely inhibited by preincubation of the sera with Hev b 6.02. N-terminal protein sequencing of 14 amino acids indicated that this 45-kD protein has a hevein-like domain at the N-terminal region and may belong to the endochitinase family. Conclusion: Latex-allergicpatients are at higher risk of becoming sensitized to Ficus. Hev b 6.02 in latex is a major cross-reactive allergen and its counterpart in F. benjamina is an acidic protein with a molecular weight of about 45 kD and a hevein-like N-terminal domain.

The Major Conformational IgE-binding Epitopes of Hevein (Hev b6.02) Are Identified by a Novel Chimera-based Allergen Epitope Mapping Strategy

“…We have also produced a number of substitution and deletion mutants of hevein. 3 A deletion mutant lacking the C terminus (amino acid residues 33-43) induced distortion of the tertiary structure and precipitation of the protein, rendering it inappropriate for adequate immunological or biochemical analyses.…”

“…In particular, health care workers (up to 17%) and children with a history of multiple surgeries (up to 60%) are reported to be sensitized to NRL products (1,2). Although several NRL allergens have recently been characterized at the molecular level, consensus exists that hevein (Hev b6.02) is one of the most important NRL allergens (3,4). Hevein (4.7 kDa, 43 amino acids) is the most predominant protein in liquid latex obtained from the rubber tree Hevea brasiliensis.…”

Construction of Hevein (Hev b 6.02) with Reduced Allergenicity for Immunotherapy of Latex Allergy by Comutation of Six Amino Acid Residues on the Conformational IgE Epitopes

“…Hevein is a small and stable protein that is recognized by ϳ70% of NRL allergic patients (10,11). Its 3-D structure has been solved (12,13) and several hevein homologues have been identified (14 -16).…”

Sensitization to Fig with Cross-Sensitization to Weeping Fig and Natural Rubber Latex

“…None of the patients showed cross-reactivity to natural rubber latex and in particular not to Hev b 6.01 and Hev b 8. Hev b 6.02 has been characterized as a crossreactive allergen in natural rubber latex and F. benjamina allergy [4]. In our patients, immunoblots showed bands at 21, 24, 27, 29 and 31 kD.…”