Screening Of PD-L1 Polypeptide Antigen And Preliminary Trial Of Its Immune Effect

Tumor therapy has been a worldwide problem.Immunotherapy has significant therapeutic effect of tumor therapy,which is a hot field of cancer research.The procedural death receptor PD-1 / PD-L1 signaling pathway plays an important role in adaptive immunity as a synergistic signal pathway for T cell immune responses.Objective: In this study,we try to Screen PD-1 / PD-L1 inhibitors that bind PD-1 to PDL1,thereby blocking the negative regulatory signal,Which can recover T cell activity and enhance the immune response.Mathod:(1)The corresponding antibody of PD-L1 polypeptide antigen was obtained by immunizing mice,and then the antibody concentration and the length of the antibody in the serum were measured by ELISA.The ability of PD-1 to compete with PD-1 and the effect of adding different adjuvant are masured by ELISA.And then we screen the peptides with a high level of immune response,which are long-lasting and highly competitive in mice.(2)Obtained by the first experiment were screened for the efficacy evaluation experiment.On the 28 th day after immunization,the mouse MC-38 tumor cells were inoculated.And the antibody concentration was measured once a week.Tumors are stripped and weighed after four weeks.The tumor pathological sections are made then.At last,we evaluate the inhibitory effect of peptides on MC-38 tumor growth through the above results.Results:(1)In the two high-titer peptide antigens of P4 and P5 were screened by the mice that were immunized twice.P4 and P5 polypeptides were found to be competitive in the competition experiment.The P4 group was higher than the P5 group.Antibody in mice in vivo growth test showed that the mice produce antibodies at the beginning of 4 weeks which immunized P4 and P5 polypeptides two groups.And the antibody concentration reached its highest value at the fifth week.The antibody of P4 group completely eliminate after 13 weeks.The antibody of P5 group completely eliminate after 11 weeks.The effect of QuickAntibody adjuvant was better in different adjuvant immunoassay experiments.(2)We find that the antibody concentration induced by P4 and P5 antigen was the highest in the fifth week after immunization in the efficacy test.The peptide concentration induced by P4 peptide was significantly different from that of the control group.While P5 group compared with the control group was not obvious.Compared with the control group,the difference of tumor size and tumor weight between the P4 and P5 experimental group was not obvious.In histopathological observation,P4 and P5 experimental group and the control was significantly different.The experimental group appeared a large area of cell necrosis and bleeding and the control group just showed that a small amount of necrosis and bleeding is not obvious.Conclutsion: P4 is the highest titer of the peptide in the PD-L1 polypeptides that synthesized in our laboratory,which may enhance the immune response to animal tumors.