Primary sequence and molecular model of the variable region of a mouse monoclonal anti-Der p 1 antibody showing a similar epitope specificity as human IgE

Background Der p 1, a major mite allergen, elicits IgE antibody responses i n 80% of patients suffering from dust mite allergy. Given the potent IgE el iciting properties of Der p 1, there is considerable interest in studying t he molecular architecture of the variable (Fv) region of IgE antibodies spe cific for this allergen. Objectives IEE is present in human serum at extremely low concentrations, a nd as such it is practically impossible to purify sufficient quantities for structural studies. We have therefore sought to sequence and model a repre sentative murine monoclonal (MoAb) anti-Der p 1 antibody, as a surrogate hu man IgE. Methods The cDNA coding for the Fv region of an anti-Der p 1 MoAb (2C7), th at mimics the binding of human IgE to Derp 1, was amplified by PCR, cloned and sequenced. The predicted amino acid sequences were then compared with a directory of human germline V-gene segments. Modelling of the Fv region of MoAb 2C7 was carried out using the extensive database of existing immunogl obulin structures in the Brookhaven PDB. Results The MoAb 2C7 heavy chain showed greater than 70% homology with thre e members of the V(H)3 family, DP-35, DP-53 and DP-54. Similarly, the light chain showed greater than 70% homology with 11 V-K sequences, including th e VKII sequences DPK18, DPK19 and DPK28. A molecular model of the Fv region of MoAb 2C7 was generated and can be accessed from the EMBL databank. Conclusions Antibodies similar to MoAb 2C7 could be generated as part of th e human repertoire. The availability of 3-dimensional model of MoAb 2C7, as a surrogate human IgE antibody, combined with further data on its epitope specificity, will facilitate studies into IgE antibody responses to Der p 1 .