[Preparation and identification of a monoclonal antibody against human PD-L1].

Objective: To prepare mouse anti-human PD-L1 monoclonal antibodies (mAbs) and identify their biological characteristics.

Methods: BALB/c mice were immunized with recombinant GST-PDL1 protein,and the strain of hybridoma cell secreting anti-PD-L1 mAb was obtained. The specificity of anti-PD-L1 mAb was checked and evaluated with ELISA and Western blot. Its titer, immunoglobulin subtype were also measured. The combining capacity of anti-PD-L1 mAb with PD-L1 on MDA-MB-231 cells, which had been induced with IFN-gamma for 72 hours, was identified through immunohistochemistry and flow cytometry. The peripheral blood mononuclear cell was labeled with CFSE, and the effect of anti-PD-L1 mAb on the activation and proliferation of the lymphocyte induced with antigens was evaluated by flow cytometry analysis.

Results: A strain of hybridoma cell secreting anti-PD-L1 mAb was successfully obtained and identified belong to IgG1 subtype. Its titers in cultural supernatant and ascetic fluid were 1:6400 and 1:102400, respectively, by ELISA. The purified mAbs showed good affinity and specificity against GST-PDL1 protein in Western blot, also could block the PD-1/PD-L1 pathway and promote the proliferation of lymphocyte induced with antigens.

Conclusion: Hyperactivity mouse anti-human PD-L1 hybridoma cell lines and their secreted monoclonal antibodies have been successfully obtained and identified.