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IDO (D5J4E™) Rabbit mAb (PE Conjugate)
Antibody Conjugates

IDO (D5J4E™) Rabbit mAb (PE Conjugate) #10312


H Endogenous Rabbit IgG
Flow Cytometry

Flow cytometric analysis of HeLa cells, untreated (blue) or treated with Human Interferon-γ (hIFN-γ) #8901 (10 ng/ml, 16 hr; green) using IDO (D5J4E™) Rabbit mAb (PE Conjugate).

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Flow Cytometry, Methanol Permeabilization Protocol for Direct Conjugates

A. Solutions and Reagents

NOTE: Prepare solutions with reverse osmosis deionized (RODI) or equivalent grade water.

  1. 20X Phosphate Buffered Saline (PBS): (#9808) To prepare 1 L 1X PBS: add 50 ml 20X PBS to 950 ml dH2O, mix.
  2. 16% Formaldehyde (methanol free).
  3. 100% methanol.
  4. Incubation Buffer: Dissolve 0.5 g Bovine Serum Albumin (BSA) (#9998) in 100 ml 1X PBS. Store at 4°C.

B. Fixation

NOTE: If using whole blood, lyse red blood cells and wash by centrifugation prior to fixation.

  1. Collect cells by centrifugation and aspirate supernatant.
  2. Resuspend cells in 0.5-1 ml 1X PBS. Add formaldehyde to obtain a final concentration of 4%.
  3. Fix for 15 min at room temperature.
  4. Wash by centrifugation with excess 1X PBS. Discard supernatant in appropriate waste container. Resuspend cells in 0.5-1 ml 1X PBS.

C. Permeabilization

  1. Permeabilize cells by adding ice-cold 100% methanol slowly to pre-chilled cells, while gently vortexing, to a final concentration of 90% methanol.
  2. Incubate 30 min on ice.
  3. Proceed with immunostaining (Section D) or store cells at -20°C in 90% methanol.

D. Immunostaining

  1. Aliquot desired number of cells into tubes or wells.
  2. Wash cells by centrifugation in excess 1X PBS to remove methanol. Discard supernatant in appropriate waste container. Repeat if necessary.
  3. Resuspend cells in 100 µl of diluted antibody conjugate (prepared in incubation buffer at the recommended dilution).
  4. Incubate for 1 hr at room temperature. Protect from light.
  5. Wash by centrifugation in incubation buffer. Discard supernatant. Repeat.
  6. Resuspend cells in 1X PBS and analyze on flow cytometer; alternatively, for DNA staining, proceed to optional DNA stain (Section E).

E. Optional DNA Dye

  1. Resuspend cells in 0.5 ml of DNA dye (e.g. Propidium Iodide (PI)/RNase Staining Solution #4087).
  2. Incubate for at least 5 min at room temperature.
  3. Analyze cells in DNA staining solution on flow cytometer.

posted July 2009

revised June 2017

Protocol Id: 407

Application Dilutions
Flow Cytometry 1:50

Supplied in PBS (pH 7.2), less than 0.1% sodium azide and 2 mg/ml BSA. Store at 4°C. Do not aliquot the antibodies. Protect from light. Do not freeze.

IDO (D5J4E™) Rabbit mAb recognizes endogenous levels of total IDO (IDO-1, INDO) protein. The antibody does not cross-react with IDO-2 (INDOL1). Some nonspecific staining of normal breast epithelium has been observed.

Species Reactivity:


Monoclonal antibody is produced by immunizing animals with recombinant human IDO protein.

This Cell Signaling Technology antibody is conjugated to phycoerythrin (PE) and tested in-house for direct flow cytometry analysis in human cells. This antibody is expected to exhibit the same species cross-reactivity as the unconjugated IDO (D5J4E™) Rabbit mAb #86630.

INDO/IDO1/indoleamine 2,3-dioxygenase (IDO) is an IFN-γ-inducible enzyme that catalyzes the rate-limiting step of tryptophan degradation (1). IDO is upregulated in many tumors and in dendritic cells in tumor-draining lymph nodes. Elevated tryptophan catabolism in these cells leads to tryptophan starvation of T cells, limiting T cell proliferation and activation (2). Therefore, IDO is considered an immunosuppresive molecule, and research studies have shown that upregulation of IDO is a mechanism of cancer immune evasion (3). The gastrointestinal stromal tumor drug, imatinib, was found to act, in part, by reducing IDO expression, resulting in increased CD8+ T cell activation and induction of apoptosis in regulatory T cells (4). In addition to its enzymatic activity, IDO was recently shown to have signaling capability through an immunoreceptor tyrosine-based inhibitory motif (ITIM) that is phosphorylated by Fyn in response to TGF-β. This leads to recruitment of SHP-1 and activation of the noncanonical NF-κB pathway (5).

  1. Yasui, H. et al. (1986) Proc Natl Acad Sci U S A 83, 6622-6.
  2. Mellor, A.L. et al. (2003) Adv Exp Med Biol 527, 27-35.
  3. Prendergast, G.C. (2008) Oncogene 27, 3889-900.
  4. Balachandran, V.P. et al. (2011) Nat Med 17, 1094-100.
  5. Pallotta, M.T. et al. (2011) Nat Immunol 12, 870-8.
Entrez-Gene Id
Swiss-Prot Acc.
For Research Use Only. Not For Use In Diagnostic Procedures.

Cell Signaling Technology is a trademark of Cell Signaling Technology, Inc.

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To Purchase # 10312S

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Product # Size Price
100 µl  (50 tests) $ 305.0

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