Immune-reactivity of recombinant isoforms of the major house dust mite allergen Der p 2

BACKGROUND: Recombinant Der p 2, expressed in yeast, lacked reactivity with 5 monoclonal antibodies against natural Der p 2. OBJECTIVE: The aim of this study was to investigate whether the lack of reactivity with recombinant Der p 2 can be explained by the existence of isoforms. METHODS: By site-directed mutagenesis three recombinant isoforms of Der p 2 were produced. Reactivity with monoclonal antibodies and human IgE was analysed by means of RAST and RAST-inhibition. RESULTS: All five monoclonals that lacked reactivity with the originally selected isoform, showed reactivity upon replacement of aspartic acid by asparagine at position 114. The other two substitutions (at position 26 and 47) had no effect. Binding of human IgE (n = 10) was not significantly influenced by the isogenetic variation at position 114. CONCLUSIONS: Monoclonal antibodies raised against natural Der p 2 can sometimes discriminate between different isoforms, allowing the study of the natural occurrence of isoforms. For application in allergen-measurement assays, non-discriminating monoclonal antibodies should be selected