Expression of the immune checkpoint B7-H3 in tumor and its soluble form in serum of patients with bone neoplasms

Abstract

B7-H3, also called CD276, is a type I transmembrane glycoprotein that is encoded on human chromosome 15. It was discovered back in 2001. The original study described it as a positive co-stimulant, as it can stimulate T-cell response and IFN-y production. However, recent researches have shown that B7-H3 is involved in T-cell inhibition. A B7-H3 receptor has not been yet identified, and this may explain the complex immunomodulatory activity of B7-H3, as it can have more than one binding partner with different functions. Expression of the B7-H3 protein has been found on activated immune cells such as T-cells, NK cells and antigen presenting cells. Interestingly, it is overexpressed in a wide range of tumor cells and is associated with disease progression and outcome. The soluble form of this protein is also of particular interest. Increased sB7-H3 levels in the plasma of bone tumor patients might be their important diagnostic criterion.