Detection of CTLA‑4 in Human PBMCs by Flow Cytometry.
Human peripheral blood mononuclear cells (PBMCs) either (A) untreated or (B) treated with 5 ug/mL PHA for 2 days were stained with Mouse Anti-Human CTLA‑4 Monoclonal Antibody (Catalog # MAB3251) followed by Allophycocyanin-conjugated Anti-Mouse IgG Secondary Antibody (Catalog # F0101B) and Mouse Anti-Human CD3 epsilon PE‑conjugated Monoclonal Antibody (Catalog # FAB100P). Quadrant markers were set based on control antibody staining (Catalog # MAB002). To facilitate intracellular staining, cells were fixed with Flow Cytometry Fixation Buffer (Catalog # FC004) and permeabilized with Flow Cytometry Permeabilization/Wash Buffer I (Catalog # FC005). View our protocol for Staining Intracellular Molecules.
Preparation and Storage
Reconstitute at 0.5 mg/mL in sterile PBS.
The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below. *Small pack size (SP) is shipped with polar packs. Upon receipt, store it immediately at -20 to -70 °C
Stability & Storage
Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
12 months from date of receipt, -20 to -70 °C as supplied.
1 month, 2 to 8 °C under sterile conditions after reconstitution.
6 months, -20 to -70 °C under sterile conditions after reconstitution.
CTLA-4 (cytotoxic T-lymphocyte associated protein‑4, designated CD152), is a type I transmembrane T cell inhibitory molecule that is a member of the Ig superfamily (1, 2). 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 68%, 71% and 83‑86% aa sequence identity with 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). Isoforms of 56-79 aa that mainly contain parts of the cytoplasmic domain are reported. 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.
Submit a review and receive a $25US/€18/£15/$25CAN amazon gift card if you include an image - $10US/€7/£6/$10CAN Amazon card for reviews without an image. Limited to verified customers in USA, Canada and Europe.