[Preparation of a novel targeted MR contrast agent Gd-DTPA-Granzyme B monoclonal antibody].

OBJECTIVE:To prepare a novel MRI targeted contrast agent Gd-DTPA-Granzyme B monoclonal antibody (mAb) and to test its reaction conditions. METHODS:The Granzyme B mAb was coupled with DTPA,and then conjugated with Gd. The Gd-DTPA antibody was characterized using MALDI-TOF-MS. Cytotoxicity test was performed with MTT assay, and immune activation was examined with immunohistochemistry. RESULT:MALDI-TOF-MS demonstrated that the molecular weight shifted from granzyme B mAb (133986) to Gd-DTPA-GB mAb (139736), which indicated the conjugation of the antibody with Gd-DTPA. The molar ratio of Gd per IgG molecule was about 20. MTT assay showed that Gd, DTPA, Gd-DTPA and Gd-DTPA-GB mAb groups did not make an impact on cell viability, and there were no significant differences among 4 groups (P>0.05). Immunohistochemistry results showed that compared with the positive control group the targeted contrast agent had a high immune activity. CONCLUSION:The novel contrast agent Gd-DTPA-Granzyme B mAb prepared in this study keeps a good immune activity and has no significant cytotoxicity.