B7-H3 [CD276] (human) ELISA Kit

B7 family of immunoregulatory proteins is composed of ten members: B7-1 (CD80), B7-2 (CD86), B7-H1 (PD-L1), B7-DC (PD-L2), B7-H2, B7-H3, B7-H4, B7-H5 (VISTA), B7-H6 and B7-H7. B7-H3 (or CD276) is a 316aa long type I transmembrane protein. B7-H3 shares 20-27% amino acid identity with other B7 family ligands. Glycosylated B7-H3 protein has a molecular weight of approximately 100 kDa. A B7-H3 'soluble' isoform has been detected in plasma and B7-H3 is also expressed on exosomes. B7-H3 is ubiquitously expressed by cells in the non-hematopoietic compartment, such as fibroblasts and epithelial cells, it can be induced on T cells and NK cells. Although B7-H3 expression is elevated in tumors, B7-H3 is also constitutively expressed at higher levels in the liver than in other healthy tissue. B7-H3 mRNA is expressed in most normal tissues, but the B7-H3 protein expression is limited in normal tissues, because of its posttranscriptional regulation by miRNAs. Specifically, miRNA-29 suppresses B7-H3 expression in normal tissues by targeting the B7-H3 3'-untranslated mRNA region. Little is known about the receptors for these B7-family ligands and their downstream signaling. TLT2 (triggering receptor expressed on myeloid cells-like transcript 2) has been characterized as a putative receptor for B7-H3, but it is dispensable for T cell response, suggesting that other unknown receptors should bind B7-H3. Although receptors remain unidentified, soluble B7-H3 has been shown to bind to CD4+ T, CD8+ T, NK and NKT cells and the extent of its binding is increased upon T cell activation. B7-H3 inhibits the activation and function of T cells, potently suppressing the proliferation, cytokine production and cytotoxicity of activated T cells. It also inhibits natural killer (NK) cell activation and has a proinflammatory role leading to cytokine release from monocytes and/or macrophages, However, B7-H3 was initially characterized as a co-stimulatory molecule required for optimal promotion of T cell proliferation and cytokine production, which makes the exact role of B7-H3 controversial. The B7-H3 [CD276] (human) ELISA Kit (Prod. No. AG-45B-0025) detects the soluble human B7-H3 (CD276) protein that is ectopically expressed in various cancers and its levels in serum of patients with cancer suggests it can be used as a noninvasive biomarker for diagnosis, prognosis and/or treatment response. Protein function: May participate in the regulation of T-cell-mediated immune response. May play a protective role in tumor cells by inhibiting natural-killer mediated cell lysis as well as a role of marker for detection of neuroblastoma cells. May be involved in the development of acute and chronic transplant rejection and in the regulation of lymphocytic activity at mucosal surfaces. Could also play a key role in providing the placenta and fetus with a suitable immunological environment throughout pregnancy. Both isoform 1 and isoform 2 appear to be redundant in their ability to modulate CD4 T-cell responses. Isoform 2 is shown to enhance the induction of cytotoxic T-cells and selectively stimulates interferon gamma production in the presence of T-cell receptor signaling. [The UniProt Consortium]