Detection And Clinical Significance Of Soluble B7-H1 In Serum

Objective: B7-H1 is one of the B7 costimulatory molecule family members. It hardly express on the surface of normal tissues. But it expresses in the tumor tissues on a high level, and the expression of the constitutive B7-H1on the tumor tissues surface is related to the oncogenesis, tumor development and prognosis. B7-H1 plays an important role in the primary reaction, activated stage of naive T cells and the secondary reaction of memory T cells respectively by the combination with its inhibitory receptors. B7-H1 induces the apoptosis of tumor antigens specific CTL and the anti-apoptosis of tumor cells. It plays an important role in tumor immunologic escape, multidrug resistence, virus infection, inflammation, anto-immune disease and the tolerance of implant. B7-H1 is a potential marker of tumor. Due to the recently research of B7-H1 were all limited to the constitutive B7-H1 on the surface of tumor cells and tissues, our preliminary research had demonstrated there was soluble B7-H1 in the serum of cancer patients, the subject planned to ascertein the existence of soluble B7-H1 in serum, then research its function and the relationship between the contents and the development of cancer; We will prepare the anti-B7H1 monoclonal antibody as there is only one such antibody on sale, establish a convinent clinical method to detect the soluble B7-H1 in serum by sandwich ELISA. Methods: First, we prepared the anti-human B7-H1 monoclonal antibody by B cell hybridoma technique. That laid the foundation to detect the soluble B7-H1 in serum. Then, we hypodermic injected SP2/0 cells into Babl/c mice and induced the formation of solid tumor. Detected the expression of soluble B7-H1 in the serum of tumor-burdened mice by these ways: (1) Ascertained the existence of soluble B7-H1 in serum of tumor-burdened mice by Dot blot. (2) Measured the molecular weight of soluble B7-H1 fragments by Western blot, and discussed the relationship between relative content of B7-H1 and the span of tumor-burdened time, tumors weight for the research of soluble B7-H1 in cancer patients serum. We finally detected the soluble and constitusive B7-H1 of lung cancer patients in these ways: (1) Ascertained the existence of soluble B7-H1 in serum of lung cancer patients. (2) Measured the molecular weight of soluble B7-H1 fragments by Western blot. (3) Established the clinical detection of soluble B7-H1 method and detected 10 lung cancer patients soluble B7-H1 contents. (4) Immunohistochemical stained the lung cancer tissues to ascertain the expression of constitutive B7-H1. Results: Injected human B7-H1IgV region mixed with adjuvant into Babl/c mice to induce the immune response, and acquired one anti-human B7-H1 monoclonal antibody with a high affinity. Serum of tumor-burdened mice detection results: (1) Dot blot results showed there do have soluble B7-H1 in tumor-burdened mice serum and with different contents respectively. (2) Western blot showed the molecular weight of the fragment was 37kD, but there didn't have obvious relativity from the contents to the span of tumor-burdened time and the tumors weight. Serum and tissues of lung cancer patients detection results: (1) Dot blot results showed there do have soluble B7-H1 in lung cancer patients serum and with different contents respectively. (2) Western blot showed the molecular weight of the fragment was 42kD. (3) Established the method to detect the content of soluble B7-H1, and detected 10 lung cancer patients serum. But we couldn't appraise the relativity from the contents to oncogenesis and development of cancer provisionally because of the lack of case imformations. (4) The immunohistochemical stain of tumor tissues results showed constitutive B7-H1 widely expressed in endochylema in tumor cells. Conclusion: Successfully prepared a anti-human B7-H1 monoclonal antibody. Established a soluble B7-H1 detection method, and successfully confirmed the presence of soluble B7-H1, laid the foundation for clinical detection. The relativity between the soluble B7-H1 and tumor development still needs further investigation.