Reatividade de anticorpos IgE a antígenos glicosilados derivados de Dermatophagoides farinae em pacientes atópicos

Abstract

Background: Components from species of mites found in the house dust showed an important role in respiratory diseases. Many of these components are glycosylated and some lectins, like Concanavalin A (ConA) showed an affinity to those molecules. Objectives: To determine the levels of speific IgE to Df crude extract and Df- ConA bound fraction in allergic patients and their cross-reaction between D. pteronyssinus and B. tropicalis crude extracts by ELISA and Inhibition ELISA, respectively. The presence of allergic components in Df crude extract and Df- ConA bound reactive to IgE by Immunoblot also was verified. Methods: Concanavalin A affinity chromatography was used to obtain glycosylated fraction with α-D-mannose and β-D-glucose residues from Dermatophagoides farinae (Df) crude extract. ConA-unbound and ConA-bound fractions and also Df crude extract were used to evaluate IgE reactivity by ELISA and Immunoblot in sera from 41 mite-sensitive patients with allergic rhinitis history and 31 non-allergic subjects selected by skin prick test. Results: All allergic patients were positive SPT to D. farinae and D. pteronyssinus, and 93% of co-positivity to B. tropicalis. ELISA showed a great positivity in all extracts, but higher levels of IgE were found in Df crude extract and ConA-unbound fractions when comparing with ConA-bound fraction. However, both ConA-unbound and ConA-bound fractions showed a significant positive correlation with Df crude extract. Inhibition ELISA assay showed a high cross-reactivity between Dermatophagoides farinae and Dermatophagoides pteronyssinus extracts. High frequency IgE reactivity to apparently high molecular bands in the ConA-bound fraction was observed by Immunoblot analysis. Conclusion: Dermatophagoides farinae represent an important source of glycosylated allergens with Concanavalin A affinity which are involved in the mechanisms of IgE induction in allergic rhinitis.