Molecular cloning, purification, and IgE-binding of a recombinant class I chitinase from Hevea brasiliensis leaves (rHev b 11.0102).

Abstract

Class I chitinase in natural rubber latex (NRL) has been assumed to be an important allergen, especially concerning its cross-reactivity with fruits like avocado and banana. The present study aimed to produce a recombinant latex class I chitinase from Hevea brasiliensis leaves and to study its immunoglobulin (Ig)E-binding reactivity. A class I chitinase-specific complementary DNA from H. brasiliensis leaves was synthesized, subcloned, sequenced and overexpressed in fusion with the maltose-binding protein (MBP) in Escherichia coli. The IgE-binding reactivity of this protein was studied by the Pharmacia CAP System and by immunoblot experiments using sera from latex-allergic patients. The rHev b 11.0102 was found to have a length of 295 amino acid residues and contains an N-terminal hevein-like domain with a 56% homology to hevein. Analysis by the CAP method revealed the presence of rHev b 11.0102-specific IgE antibodies in 17 of 58 sera (29%) of IgE-mediated latex-allergic subjects tested. Immunoblot analysis of the MBP-rHev b 11.0102 fusion protein and the MBP carrier protein as a negative control confirmed the IgE-reactivity of rHev b 11.0102. Due to its IgE-reactivity rHev b 11.0102 represents an allergen of intermediate prevalence in NRL. Its property to cross-react with certain fruits makes it an important supplement in the diagnostic panel of recombinant NRL allergens.