Preparation and application of a novel monoclonal antibody specific for human B7-H3.

Human B7-H3 (CD276), as a new member of the B7 family has been demonstrated to mediate T cell proliferation and the production of interferon‑γ. Two isoforms of B7-H3 have been identified in humans, 2IgB7‑H3 and 4IgB7‑H3. Since the costimulatory functions of the two isoforms remains to be fully elucidated, there are disagreements regarding their expression patterns as well as the T cell responses. In the present study, a single mouse anti‑human monoclonal antibody (mAb), specific for 2IgB7‑H3 and 4IgB7‑H3 was established, termed 11F4. Using this antibody, the expression of B7‑H3 was observed extensively in tumor cell lines, with the exception of certain human hematopoietic cell lines. Subsequently, the fusion proteins of the two B7‑H3 isoforms were produced to analyze the biological function of 4IgB7‑H3 and 2IgB7‑H3 using a Cell Counting Kit‑8 assay, and the data revealed that the two isoforms exhibited a similar function in promoting T cell proliferation. In addition, the effect of B7‑H3 on the T cells was inhibited by the 11F4 mAb. Overall, the novel antibody produced was observed to exhibit an inhibitory effect offering a useful tool in further investigations of the function of B7-H3 isoforms.