Identification of antigenic peptide recognized by the anti-JL1 leukemia-specific monoclonal antibody from combinatorial peptide phage display libraries.

摘要

PURPOSE. In the present study an antigen-mimetic peptide of the anti-JL1 leukemia-specific monoclonal antibody (mAb) was identified and characterized. METHODS. From combinatorial peptide phage display libraries displaying the random linear heptapeptides and dodecapeptides, we selected clones with affinity to anti-JL1 mAb through repeated rounds of panning on a mAb-coated ELISA plate. The antigenicity and immunogenicity of the peptide epitopes were then studied using chemically synthesized peptides. RESULTS. The selected clones had the LXPSIP consensus sequence. Two synthetic peptides LPPSIPFGLTVGGGGS and LLPSIPNQAYLGGGGS specifically reacted with anti-JL1 mAb in ELISA. These two peptides were found to inhibit the interaction between anti-JL1 mAb and JL1 antigen-positive Molt-4 cells. Although the immune sera raised against the keyhole limpet hemocyanin-conjugated peptides failed to react with Molt-4 cells, it showed strong reactivity to the peptide epitope. However, one mAb raised by peptide immunization successfully bound to Molt-4 cells. CONCLUSION. An epitope-mimetic peptide of anti-JL1 mAb was found using combinatorial peptide phage display libraries. It induced strong humoral response against itself, but only a limited fraction of this humoral response was cross-reactive with the original JL1 antigen.