Background: Der p 2, composed of 129 amino acids, is one of the major allergens of Dermatophagoides pteronyssinus. Several groups reported epitope mapping of IgE antibody but not of IgG or IgG subclass antibodies in Der p 2.
Objective: The purpose of this study was to compare the epitopes recognized by Der p 2-specific IgE antibodies with those recognized by IgG4 antibodies.
Methods: Recombinant fusion proteins containing a full-length peptide or overlapping five fragments of Der p 2 were prepared and analyzed for their reactivity with IgE and IgG subclass antibodies in sera from patients with mite allergy by means of Western blot procedure.
Results: IgE antibodies in 12 of 13 sera tested bound to full-length Der p 2 (1-129). In 11 of these 12 sera, IgE antibodies bound to one or more of fragments 41-80, 64-105, or 81-129 but not to those of 1-40 or 20-63. Of the 11 sera in which the IgE antibodies to the fragments were detected, only four contained detectable levels of IgG4 antibodies reactive to the fragments. The binding spectra of the IgG4 antibodies against the fragments were rather wide and differed from those of IgE antibodies.
Conclusion: Results revealed that there are differences in epitope recognition between IgE and IgG4 antibodies; IgE antibodies recognize restricted parts of Der p 2 antigen compared with IgG4.