Cell Line

Recombinant CHO-K1 cells stably overexpress V-domain Ig suppressor of T cell activation (VISTA) on the cell surface. The surface expression of VISTA is validated by FACS analysis. This cell line is designed for cell-based binding for screening antibodies binding with VISTA and evaluating target binding affinity.

The B and T lymphocyte attenuator (BTLA) is an Ig super family protein with an intermediate type Ig fold in the ectodomain and an ITIM inhibitory signaling domain in the cytosol. BTLA interacts with the herpesvirus entry mediator (HVEM; TNFRSF14), a TNFR super family member. Engagement of BTLA by HVEM, induces tyrosine phosphorylation of the ITIM motifs in the cytoplasmic tail of BTLA, allowing the recruitment of the phosphatases SHP-1 and SHP-2, which attenuate signaling.

B7-H3, a new member of the B7 family of immune-regulatory molecules, was identified in 2001 by database searches of a human dendritic cell-derived cDNA library. It is a type I transmembrane protein, which expresses in certain normal cells and tissues, such as dendritic cells, as well as the liver, lung, breast, placenta, and prostate. Aberrant expression of B7-H3 has been reported in a wide range of solid cancers, including brain, lung, pancreatic, colorectal, liver, and breast cancers, as well as in hematologic malignancies, such as acute leukemia and multiple myeloma, and it is associated with more advanced disease and poor prognosis.

B7-H4 is a transmembrane protein that binds an unknown receptor on activated T cells resulting in inhibition of T-cell effector function via cell cycle arrest, decreased proliferation, and reduced IL-2 production. B7-H4 is up-regulated on the surface of cancer cells and immunosuppressive tumor-associated macrophages (TAMs) in a variety of human cancers.

CD137 is a member of the tumor necrosis factor (TNF) receptor family. Its alternative names are tumor necrosis factor receptor superfamily member 9 (TNFRSF9), 4-1BB and induced by lymphocyte activation (ILA). It is currently of interest to immunologists as a co-stimulatory immune checkpoint molecule.

Tumor necrosis factor receptor superfamily member 18 (TNFRSF18) also known as activation-inducible TNFR family receptor (AITR) or glucocorticoid-induced TNFR-related protein (GITR) is a protein that in humans is encoded by the TNFRSF18 gene. GITR is currently of interest to immunologists as a co-stimulatory immune checkpoint molecule.

Cell surface glycoprotein CD200 receptor 1 is a protein that in humans is encoded by the CD200R1 gene. This gene encodes a receptor for the OX-2 membrane glycoprotein. Both the receptor and substrate are cell surface glycoproteins containing two immunoglobulin-like domains. This receptor is restricted to the surfaces of myeloid lineage cells and the receptor-substrate interaction may function as a myeloid downregulatory signal. Mouse studies of a related gene suggest that this interaction may control myeloid function in a tissue-specific manner.

TIGIT (T cell immunoreceptor with Ig and ITIM domains) was recently characterized as an inhibitory receptor, which is expressed mainly on NK, Treg, CD8+ T, and CD4+ T cells. TIGIT harbors an immunoglobulin tail tyrosine (ITT)-like phosphorylation motif and an ITIM (immunoreceptor tyrosine-based inhibition motif) in its cytoplasmic tail. The poliovirus receptor (PVR or CD155) was identified as the physical ligand of TIGIT with high affinity, and PVRL2 (Nectin2 or CD112) also binds to TIGIT with a weaker binding capacity. TIGIT/PVR engagement suppresses T cell activation through IL-10 secretion mediated by dendritic cells. Furthermore, TIGIT also exerts an intrinsic inhibitory function to T cell activation.

Recombinant CHO-K1 cells stably overexpress Homo sapiens programmed death-ligand 1 (PD-L1) on the cell surface. The surface expression is validated by FACS analysis. This cell line is recommended for cell-based binding assay to screen antibodies against PD-L1 or to measure binding affinity between PD-L1 and anti-PD-L1 antibodies.