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-gamma 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.