Mouse/human chimeric IgGl and IgG4 antibodies directed to the house dust mite allergen Der p 2: use in quantification of allergen specific IgG

Background and Objective Chimeric mouse/human monoclonal IgGl and IgG4 antibodies were developed against the house dust mite allergen Der p 2. These chimeric IgG antibodies, hIgG1-Dp2 A and hIgG4-Dp2 A, have the same binding characteristics as the previously reported chimeric hIgE-Dp2 A and are composed of the heavy chain variable domains and light chains ot the original murine monoclonal antibody 2B12., whereas the heavy chain constant domains have been replaced by the human IgGl or IgG4 heavy chain. The expression level of hIgG1-Dp2 A and hIgG4-Dp2 A was 1 and 3.5 μg/mL, respectively. Methods and Results Since all IgG in these culture supernatants is allergen-specific. they are useful reference reagents and enable the calculation of the amount of allergen specific IgG l and IgG4 antibodies in absolute IgG amounts. The results obtained with two panels of sera from patients in immunotherapeutic treatment were evaluated and compared in Der p 2 IgE, IgGl and IgG4 RAST and with reversed lgG4 RAST using labelled purified Der p 2. Close agreement between the results for the two IgG4 assays was found. Conclusion With these chimeric reference reagents the quantities of isotype specific antiallergen antibodies can be calculated and compared.