Fusarium solani major allergen peptide IV-1 binds IgE but does not release histamine

Abstract

Background: Fusarium solani (FS) is an important allergen source afflicting 4% of the nasobronchial allergy patients. Fus s I₃₅₉₆^∗, a 65 kDa major glycoprotein allergen of FS reacts with 95% fungus sensitive patients. Objectives: To purify and characterize a potent peptide from Fus s I₃₅₉₆^∗ which may be useful for therapeutic purposes. Methods: The 65 kDa protein was sequentially cleaved with trypsin and cyanogen bromide (CNBr). The cleaved products were purified on reverse phase high performance liquid chromatography (rpHPLC) column and functionally characterized by in vitro and in vivo methods for its IgE binding and histamine release. Results: The protein on cleavage showed 11 peaks (I to XI). Of these, peaks I, III, IV and V were highly allergenic as determined by IgE ELISA. These peaks were further purified and peptide IV-1 was most potent in comparison to other peptides by ELISA-inhibition. This peptide showed IgE binding but could not evoke intradermal response in Fusarium-sensitive patients. Heparinized blood challenged with peptide IV-1 does not release histamine. Preincubation of heparinized blood with peptide IV-1 and challenging with crude extract blocked histamine release in a dose dependent manner. Conclusion: Peptide IV-1 binds to IgE but does not release histamine, demonstrating its potential use in therapy of Fusarium-allergic patients.