>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
<0.10 EU per 1 μg of the protein by the LAL method.
Measured by its binding ability in a functional ELISA. When Recombinant Cynomolgus Monkey CTLA‑4 Fc Chimera is coated at 0.5 µg/mL, 100 μL/well,
Human B7‑1/CD80 Fc Chimera (Catalog # 140-B1)
binds with an ED50 of 5-30 ng/mL.
When Recombinant Cynomolgus Monkey CTLA‑4 FcChimera (Catalog # 9336-CT) is coated at 0.5 µg/mL,100 μL/well, Recombinant Human B7‑1/CD80 Fc Chimera (Catalog # 140-B1) binds with anED50 of 5-30 ng/mL.
CTLA-4 (cytotoxic T-lymphocyte-4, designated CD152), is a
type I transmembrane T cell inhibitory molecule that is a member of the Ig
superfamily (1, 2). Cyno CTLA-4 has a 98% homology to human CTLA-4. Human or
mouse CTLA-4 cDNA encodes 223 amino acids (aa) including a 35 aa signal
sequence, a 126 aa extracellular domain (ECD) with one Ig-like V-type domain, a
21 aa transmembrane (TM) sequence, and a 41 aa cytoplasmic sequence. It is
found as a covalent homodimer of 41-43 kDa (2). Within the ECD, human CTLA-4
shares 98%, 68%, 71% and 83-86% aa sequence identity with cynomolgus, mouse,
rat and porcine/bovine/rabbit/feline/canine CTLA-4, respectively. A 174 aa form
that lacks TM and cytoplasmic sequences (sCTLA-4) is possibly secreted (3-5). In mouse, an isoform lacking the Ig-like
domain has ligand-independent inhibitory activity and is termed liCTLA-4 (6).
CD28, which is structurally related to CTLA-4, is constitutively expressed on
naïve T cells and promotes T cell activation when engaged by B7-2 on
antigen-presenting cells (APC) within the immunological synapse (IS) (1, 7, 8).
In contrast, CTLA-4 is recruited from intracellular vesicles to the IS
beginning 1-2 days after T cell activation (2, 7, 8). It forms a linear lattice
with B7-1 on APC, inducing negative regulatory signals and ending T cell
activation (9). Abatacept, a therapeutic human CTLA-4-Ig fusion protein (trade
name Orencia), competes with CD28 for B7-1 and B7-2 binding and has been used
to antagonize T cell activation in autoimmune conditions and to enhance
transplant survival (10). Mice deleted for CTLA-4 show no abnormalities until
after birth, but then develop lethal autoimmune reactions due to continued T
cell activation and poor control by regulatory T cells, which constitutively
express CTLA-4 in wild-type mice and humans (11-13).
Harper, K. et al. (1991) J. Immunol. 147:1037.
Teft, W.A. et al. (2006) Annu. Rev. Immunol. 24:65.
Magistrelli, G. et al. (1999) Eur. J. Immunol. 29:3596.
Tector, M. et al. (2009) BMC Immunol. 10:51.
Oaks, M.K. and K.M. Hallett (2000) J. Immunol. 164:5015.
Vijayakrishnan, L. et al. (2004) Immunity 20:563.
Pentcheva-Hoang, T. et al. (2004) Immunity 21:401.
Jansson, A. et al. (2005) J. Immunol 175:1575.
Darlington, P.J. et al. (2005) J. Immunol. 175:996.
Platt, A.M. et al. (2010) J. Immunol. 185:1558.
Wing, K. et al. (2008) Science. 322: 271.
Friedline, R.H. et al. (2009) J. Exp. Med. 206:421.
Jain, N. et al. (2010) Proc. Natl. Acad. Sci. USA. 107:1524.
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